diff --git a/ruma-events-macros/src/gen.rs b/ruma-events-macros/src/gen.rs
index 18f52318..4c788908 100644
--- a/ruma-events-macros/src/gen.rs
+++ b/ruma-events-macros/src/gen.rs
@@ -87,9 +87,10 @@ impl ToTokens for RumaEvent {
 
         let content = match &self.content {
             Content::Struct(fields) => {
+                // TODO remove serde::Deserialize when this macro actually generates generic events
                 quote! {
                     #[doc = #content_docstring]
-                    #[derive(Clone, Debug, serde::Serialize)]
+                    #[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
                     pub struct #content_name {
                         #(#fields),*
                     }
diff --git a/src/lib.rs b/src/lib.rs
index 6f1106dd..8f82b46d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -119,7 +119,6 @@
 use std::fmt::Debug;
 
 use js_int::Int;
-use ruma_identifiers::{EventId, RoomId, UserId};
 use serde::{Deserialize, Serialize};
 
 // use self::room::redaction::RedactionEvent;
@@ -165,6 +164,7 @@ pub mod receipt;
 pub mod room;
 // pub mod room_key;
 pub mod room_key_request;
+pub mod state;
 pub mod sticker;
 // pub mod stripped;
 pub mod tag;
@@ -211,3 +211,23 @@ impl UnsignedData {
         //   && self.redacted_because.is_none()
     }
 }
+
+/// The base trait that all event content types implement.
+///
+/// Implementing this trait allows content types to be serialized as well as deserialized.
+pub trait EventContent: Sized + Serialize {
+    /// Constructs the given event content.
+    fn from_parts(
+        event_type: &str,
+        content: &serde_json::value::RawValue,
+    ) -> Result<Self, InvalidEvent>;
+
+    /// A matrix event identifier, like `m.room.message`.
+    fn event_type(&self) -> &str;
+}
+
+/// Marker trait for room events.
+pub trait RoomEventContent: EventContent {}
+
+/// Marker trait for state events.
+pub trait StateEventContent: RoomEventContent {}
diff --git a/src/room/aliases.rs b/src/room/aliases.rs
index 2c1cab8b..72677307 100644
--- a/src/room/aliases.rs
+++ b/src/room/aliases.rs
@@ -2,6 +2,12 @@
 
 use ruma_events_macros::ruma_event;
 use ruma_identifiers::RoomAliasId;
+use serde_json::value::RawValue as RawJsonValue;
+
+use crate::{
+    error::{InvalidEvent, InvalidEventKind},
+    EventContent, RoomEventContent, StateEventContent,
+};
 
 ruma_event! {
     /// Informs the room about what room aliases it has been given.
@@ -14,3 +20,26 @@ ruma_event! {
         },
     }
 }
+
+impl EventContent for AliasesEventContent {
+    fn event_type(&self) -> &str {
+        "m.room.aliases"
+    }
+
+    fn from_parts(event_type: &str, content: &RawJsonValue) -> Result<Self, InvalidEvent> {
+        if event_type != "m.room.aliases" {
+            return Err(InvalidEvent {
+                kind: InvalidEventKind::Deserialization,
+                message: format!("expected `m.room.aliases` found {}", event_type),
+            });
+        }
+        serde_json::from_str::<AliasesEventContent>(content.get()).map_err(|e| InvalidEvent {
+            kind: InvalidEventKind::Deserialization,
+            message: e.to_string(),
+        })
+    }
+}
+
+impl RoomEventContent for AliasesEventContent {}
+
+impl StateEventContent for AliasesEventContent {}
diff --git a/src/room/avatar.rs b/src/room/avatar.rs
index 2ec7dbb1..54304a80 100644
--- a/src/room/avatar.rs
+++ b/src/room/avatar.rs
@@ -1,8 +1,13 @@
 //! Types for the *m.room.avatar* event.
 
 use ruma_events_macros::ruma_event;
+use serde_json::value::RawValue as RawJsonValue;
 
 use super::ImageInfo;
+use crate::{
+    error::{InvalidEvent, InvalidEventKind},
+    EventContent, RoomEventContent, StateEventContent,
+};
 
 ruma_event! {
     /// A picture that is associated with the room.
@@ -22,3 +27,26 @@ ruma_event! {
         },
     }
 }
+
+impl EventContent for AvatarEventContent {
+    fn event_type(&self) -> &str {
+        "m.room.avatar"
+    }
+
+    fn from_parts(event_type: &str, content: &RawJsonValue) -> Result<Self, InvalidEvent> {
+        if event_type != "m.room.avatar" {
+            return Err(InvalidEvent {
+                kind: InvalidEventKind::Deserialization,
+                message: format!("expected `m.room.avatar` found {}", event_type),
+            });
+        }
+        serde_json::from_str::<AvatarEventContent>(content.get()).map_err(|e| InvalidEvent {
+            kind: InvalidEventKind::Deserialization,
+            message: e.to_string(),
+        })
+    }
+}
+
+impl RoomEventContent for AvatarEventContent {}
+
+impl StateEventContent for AvatarEventContent {}
diff --git a/src/state.rs b/src/state.rs
new file mode 100644
index 00000000..cb44c19d
--- /dev/null
+++ b/src/state.rs
@@ -0,0 +1,498 @@
+//! An enum that represents any state event. A state event is represented by
+//! a parameterized struct allowing more flexibility in whats being sent.
+
+use std::{
+    convert::TryFrom,
+    fmt,
+    marker::PhantomData,
+    time::{Duration, SystemTime, UNIX_EPOCH},
+};
+
+use js_int::UInt;
+use ruma_identifiers::{EventId, RoomId, UserId};
+use serde::{
+    de::{self, Deserialize, Deserializer, Error as _, MapAccess, Visitor},
+    ser::{Error, SerializeStruct},
+    Serialize, Serializer,
+};
+use serde_json::value::RawValue as RawJsonValue;
+
+use crate::{
+    error::{InvalidEvent, InvalidEventKind},
+    room::{aliases::AliasesEventContent, avatar::AvatarEventContent},
+    EventContent, RoomEventContent, StateEventContent,
+};
+
+/// A state event.
+#[derive(Clone, Debug, Serialize)]
+#[serde(untagged)]
+#[allow(clippy::large_enum_variant)]
+pub enum AnyStateEventContent {
+    /// m.room.aliases
+    RoomAliases(AliasesEventContent),
+
+    /// m.room.avatar
+    RoomAvatar(AvatarEventContent),
+    // /// m.room.canonical_alias
+    // RoomCanonicalAlias(StateEvent<CanonicalAliasEventContent>),
+
+    // /// m.room.create
+    // RoomCreate(StateEvent<CreateEventContent>),
+
+    // /// m.room.encryption
+    // RoomEncryption(StateEvent<EncryptionEventContent>),
+
+    // /// m.room.guest_access
+    // RoomGuestAccess(StateEvent<GuestAccessEventContent>),
+
+    // /// m.room.history_visibility
+    // RoomHistoryVisibility(StateEvent<HistoryVisibilityEventContent>),
+
+    // /// m.room.join_rules
+    // RoomJoinRules(StateEvent<JoinRulesEventContent>),
+
+    // /// m.room.member
+    // RoomMember(StateEvent<MemberEventContent>),
+
+    // /// m.room.name
+    // RoomName(StateEvent<NameEventContent>),
+
+    // /// m.room.pinned_events
+    // RoomPinnedEvents(StateEvent<PinnedEventsEventContent>),
+
+    // /// m.room.power_levels
+    // RoomPowerLevels(StateEvent<PinnedEventsEventContent>),
+
+    // /// m.room.server_acl
+    // RoomServerAcl(StateEvent<ServerAclEventContent>),
+
+    // /// m.room.third_party_invite
+    // RoomThirdPartyInvite(StateEvent<ThirdPartyInviteEventContent>),
+
+    // /// m.room.tombstone
+    // RoomTombstone(StateEvent<TombstoneEventContent>),
+
+    // /// m.room.topic
+    // RoomTopic(StateEvent<TopicEventContent>),
+
+    // /// Any state event that is not part of the specification.
+    // CustomState(StateEvent<CustomEventContent>),
+}
+
+/// To-device event.
+#[derive(Clone, Debug)]
+pub struct StateEvent<C: StateEventContent> {
+    /// Data specific to the event type.
+    pub content: C,
+
+    /// The globally unique event identifier for the user who sent the event.
+    pub event_id: EventId,
+
+    /// Contains the fully-qualified ID of the user who sent this event.
+    pub sender: UserId,
+
+    /// Timestamp in milliseconds on originating homeserver when this event was sent.
+    pub origin_server_ts: SystemTime,
+
+    /// The ID of the room associated with this event.
+    pub room_id: RoomId,
+
+    /// A unique key which defines the overwriting semantics for this piece of room state.
+    ///
+    /// This is often an empty string, but some events send a `UserId` to show
+    /// which user the event affects.
+    pub state_key: String,
+
+    /// Optional previous content for this event.
+    pub prev_content: Option<C>,
+}
+
+impl EventContent for AnyStateEventContent {
+    fn event_type(&self) -> &str {
+        match self {
+            AnyStateEventContent::RoomAliases(content) => content.event_type(),
+            AnyStateEventContent::RoomAvatar(content) => content.event_type(),
+        }
+    }
+
+    fn from_parts(event_type: &str, content: &RawJsonValue) -> Result<Self, InvalidEvent> {
+        fn deserialize_variant<T: StateEventContent>(
+            ev_type: &str,
+            input: &RawJsonValue,
+            variant: fn(T) -> AnyStateEventContent,
+        ) -> Result<AnyStateEventContent, InvalidEvent> {
+            let content = T::from_parts(ev_type, input)?;
+            Ok(variant(content))
+        }
+
+        match event_type {
+            "m.room.avatar" => deserialize_variant::<AvatarEventContent>(
+                event_type,
+                content,
+                AnyStateEventContent::RoomAvatar,
+            ),
+            "m.room.aliases" => deserialize_variant::<AliasesEventContent>(
+                event_type,
+                content,
+                AnyStateEventContent::RoomAliases,
+            ),
+            ev => Err(InvalidEvent {
+                kind: InvalidEventKind::Deserialization,
+                message: format!("event not supported {}", ev),
+            }),
+        }
+    }
+}
+
+impl RoomEventContent for AnyStateEventContent {}
+
+impl StateEventContent for AnyStateEventContent {}
+
+impl<C: StateEventContent> Serialize for StateEvent<C> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let event_type = self.content.event_type();
+
+        let time_since_epoch = self.origin_server_ts.duration_since(UNIX_EPOCH).unwrap();
+        let timestamp = match UInt::try_from(time_since_epoch.as_millis()) {
+            Ok(uint) => uint,
+            Err(err) => return Err(S::Error::custom(err)),
+        };
+
+        let mut state = serializer.serialize_struct("StateEvent", 7)?;
+        state.serialize_field("content", &self.content)?;
+        state.serialize_field("event_id", &self.event_id)?;
+        state.serialize_field("sender", &self.sender)?;
+        state.serialize_field("origin_server_ts", &timestamp)?;
+        state.serialize_field("room_id", &self.room_id)?;
+        state.serialize_field("state_key", &self.state_key)?;
+        if let Some(content) = self.prev_content.as_ref() {
+            state.serialize_field("prev_content", content)?;
+        }
+        state.serialize_field("type", event_type)?;
+        state.end()
+    }
+}
+
+impl<'de, C: StateEventContent> Deserialize<'de> for StateEvent<C> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_map(StateEventVisitor(std::marker::PhantomData))
+    }
+}
+
+#[derive(serde::Deserialize)]
+#[serde(field_identifier, rename_all = "snake_case")]
+enum Field {
+    Type,
+    Content,
+    EventId,
+    Sender,
+    OriginServerTs,
+    RoomId,
+    StateKey,
+    PrevContent,
+}
+
+/// Visits the fields of a StateEvent<C> to handle deserialization of
+/// the `content` and `prev_content` fields.
+struct StateEventVisitor<C: StateEventContent>(PhantomData<C>);
+
+impl<'de, C: StateEventContent> Visitor<'de> for StateEventVisitor<C> {
+    type Value = StateEvent<C>;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(formatter, "struct implementing StateEventContent")
+    }
+
+    fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
+    where
+        A: MapAccess<'de>,
+    {
+        let mut content: Option<Box<RawJsonValue>> = None;
+        let mut event_type: Option<String> = None;
+        let mut event_id: Option<EventId> = None;
+        let mut sender: Option<UserId> = None;
+        let mut origin_server_ts: Option<UInt> = None;
+        let mut room_id: Option<RoomId> = None;
+        let mut state_key: Option<String> = None;
+        let mut prev_content: Option<Box<RawJsonValue>> = None;
+
+        while let Some(key) = map.next_key()? {
+            match key {
+                Field::Content => {
+                    if content.is_some() {
+                        return Err(de::Error::duplicate_field("content"));
+                    }
+                    content = Some(map.next_value()?);
+                }
+                Field::EventId => {
+                    if event_id.is_some() {
+                        return Err(de::Error::duplicate_field("event_id"));
+                    }
+                    event_id = Some(map.next_value()?);
+                }
+                Field::Sender => {
+                    if sender.is_some() {
+                        return Err(de::Error::duplicate_field("sender"));
+                    }
+                    sender = Some(map.next_value()?);
+                }
+                Field::OriginServerTs => {
+                    if origin_server_ts.is_some() {
+                        return Err(de::Error::duplicate_field("origin_server_ts"));
+                    }
+                    origin_server_ts = Some(map.next_value()?);
+                }
+                Field::RoomId => {
+                    if room_id.is_some() {
+                        return Err(de::Error::duplicate_field("room_id"));
+                    }
+                    room_id = Some(map.next_value()?);
+                }
+                Field::StateKey => {
+                    if state_key.is_some() {
+                        return Err(de::Error::duplicate_field("state_key"));
+                    }
+                    state_key = Some(map.next_value()?);
+                }
+                Field::PrevContent => {
+                    if prev_content.is_some() {
+                        return Err(de::Error::duplicate_field("prev_content"));
+                    }
+                    prev_content = Some(map.next_value()?);
+                }
+                Field::Type => {
+                    if event_type.is_some() {
+                        return Err(de::Error::duplicate_field("type"));
+                    }
+                    event_type = Some(map.next_value()?);
+                }
+            }
+        }
+
+        let event_type = event_type.ok_or_else(|| de::Error::missing_field("type"))?;
+
+        let raw = content.ok_or_else(|| de::Error::missing_field("content"))?;
+        let content = C::from_parts(&event_type, &raw).map_err(A::Error::custom)?;
+
+        let event_id = event_id.ok_or_else(|| de::Error::missing_field("event_id"))?;
+        let sender = sender.ok_or_else(|| de::Error::missing_field("sender"))?;
+
+        let origin_server_ts = origin_server_ts
+            .map(|time| UNIX_EPOCH + Duration::from_millis(time.into()))
+            .ok_or_else(|| de::Error::missing_field("origin_server_ts"))?;
+
+        let room_id = room_id.ok_or_else(|| de::Error::missing_field("room_id"))?;
+        let state_key = state_key.ok_or_else(|| de::Error::missing_field("state_key"))?;
+
+        let prev_content = if let Some(raw) = prev_content {
+            Some(C::from_parts(&event_type, &raw).map_err(A::Error::custom)?)
+        } else {
+            None
+        };
+
+        Ok(StateEvent {
+            content,
+            event_id,
+            sender,
+            origin_server_ts,
+            room_id,
+            state_key,
+            prev_content,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::{
+        convert::TryFrom,
+        time::{Duration, UNIX_EPOCH},
+    };
+
+    use js_int::UInt;
+    use matches::assert_matches;
+    use ruma_identifiers::{EventId, RoomAliasId, RoomId, UserId};
+    use serde_json::{from_value as from_json_value, json, to_value as to_json_value};
+
+    use super::{AliasesEventContent, AnyStateEventContent, AvatarEventContent, StateEvent};
+    use crate::room::{ImageInfo, ThumbnailInfo};
+
+    #[test]
+    fn serialize_aliases_with_prev_content() {
+        let aliases_event = StateEvent {
+            content: AnyStateEventContent::RoomAliases(AliasesEventContent {
+                aliases: vec![RoomAliasId::try_from("#somewhere:localhost").unwrap()],
+            }),
+            event_id: EventId::try_from("$h29iv0s8:example.com").unwrap(),
+            origin_server_ts: UNIX_EPOCH + Duration::from_millis(1),
+            prev_content: Some(AnyStateEventContent::RoomAliases(AliasesEventContent {
+                aliases: vec![RoomAliasId::try_from("#somewhere:localhost").unwrap()],
+            })),
+            room_id: RoomId::try_from("!roomid:room.com").unwrap(),
+            sender: UserId::try_from("@carl:example.com").unwrap(),
+            state_key: "".to_string(),
+        };
+
+        let actual = to_json_value(&aliases_event).unwrap();
+        let expected = json!({
+            "content": {
+                "aliases": [ "#somewhere:localhost" ]
+            },
+            "event_id": "$h29iv0s8:example.com",
+            "origin_server_ts": 1,
+            "prev_content": {
+                "aliases": [ "#somewhere:localhost" ]
+            },
+            "room_id": "!roomid:room.com",
+            "sender": "@carl:example.com",
+            "state_key": "",
+            "type": "m.room.aliases",
+        });
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn serialize_aliases_without_prev_content() {
+        let aliases_event = StateEvent {
+            content: AnyStateEventContent::RoomAliases(AliasesEventContent {
+                aliases: vec![RoomAliasId::try_from("#somewhere:localhost").unwrap()],
+            }),
+            event_id: EventId::try_from("$h29iv0s8:example.com").unwrap(),
+            origin_server_ts: UNIX_EPOCH + Duration::from_millis(1),
+            prev_content: None,
+            room_id: RoomId::try_from("!roomid:room.com").unwrap(),
+            sender: UserId::try_from("@carl:example.com").unwrap(),
+            state_key: "".to_string(),
+        };
+
+        let actual = to_json_value(&aliases_event).unwrap();
+        let expected = json!({
+            "content": {
+                "aliases": [ "#somewhere:localhost" ]
+            },
+            "event_id": "$h29iv0s8:example.com",
+            "origin_server_ts": 1,
+            "room_id": "!roomid:room.com",
+            "sender": "@carl:example.com",
+            "state_key": "",
+            "type": "m.room.aliases",
+        });
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn deserialize_aliases_with_prev_content() {
+        let json_data = json!({
+            "content": {
+                "aliases": [ "#somewhere:localhost" ]
+            },
+            "event_id": "$h29iv0s8:example.com",
+            "origin_server_ts": 1,
+            "prev_content": {
+                "aliases": [ "#inner:localhost" ]
+            },
+            "room_id": "!roomid:room.com",
+            "sender": "@carl:example.com",
+            "state_key": "",
+            "type": "m.room.aliases"
+        });
+
+        assert_matches!(
+            from_json_value::<StateEvent<AnyStateEventContent>>(json_data).unwrap(),
+            StateEvent {
+                content: AnyStateEventContent::RoomAliases(content),
+                event_id,
+                origin_server_ts,
+                prev_content: Some(AnyStateEventContent::RoomAliases(prev_content)),
+                room_id,
+                sender,
+                state_key,
+            } if content.aliases == vec![RoomAliasId::try_from("#somewhere:localhost").unwrap()]
+                && event_id == EventId::try_from("$h29iv0s8:example.com").unwrap()
+                && origin_server_ts == UNIX_EPOCH + Duration::from_millis(1)
+                && prev_content.aliases == vec![RoomAliasId::try_from("#inner:localhost").unwrap()]
+                && room_id == RoomId::try_from("!roomid:room.com").unwrap()
+                && sender == UserId::try_from("@carl:example.com").unwrap()
+                && state_key == ""
+        );
+    }
+
+    #[test]
+    fn deserialize_avatar_without_prev_content() {
+        let json_data = json!({
+            "content": {
+                "info": {
+                    "h": 423,
+                    "mimetype": "image/png",
+                    "size": 84242,
+                    "thumbnail_info": {
+                      "h": 334,
+                      "mimetype": "image/png",
+                      "size": 82595,
+                      "w": 800
+                    },
+                    "thumbnail_url": "mxc://matrix.org",
+                    "w": 1011
+                  },
+                "url": "http://www.matrix.org"
+            },
+            "event_id": "$h29iv0s8:example.com",
+            "origin_server_ts": 1,
+            "room_id": "!roomid:room.com",
+            "sender": "@carl:example.com",
+            "state_key": "",
+            "type": "m.room.avatar"
+        });
+
+        assert_matches!(
+            from_json_value::<StateEvent<AnyStateEventContent>>(json_data).unwrap(),
+            StateEvent {
+                content: AnyStateEventContent::RoomAvatar(AvatarEventContent {
+                    info: Some(ImageInfo {
+                        height,
+                        width,
+                        mimetype: Some(mimetype),
+                        size,
+                        thumbnail_info: Some(ThumbnailInfo {
+                            width: thumb_width,
+                            height: thumb_height,
+                            mimetype: thumb_mimetype,
+                            size: thumb_size,
+                        }),
+                        thumbnail_url: Some(thumbnail_url),
+                        thumbnail_file: None,
+                    }),
+                    url,
+                }),
+                event_id,
+                origin_server_ts,
+                prev_content: None,
+                room_id,
+                sender,
+                state_key,
+            } if event_id == EventId::try_from("$h29iv0s8:example.com").unwrap()
+                && origin_server_ts == UNIX_EPOCH + Duration::from_millis(1)
+                && room_id == RoomId::try_from("!roomid:room.com").unwrap()
+                && sender == UserId::try_from("@carl:example.com").unwrap()
+                && state_key == ""
+                && height == UInt::new(423)
+                && width == UInt::new(1011)
+                && mimetype == "image/png"
+                && size == UInt::new(84242)
+                && thumb_width == UInt::new(800)
+                && thumb_height == UInt::new(334)
+                && thumb_mimetype == Some("image/png".to_string())
+                && thumb_size == UInt::new(82595)
+                && thumbnail_url == "mxc://matrix.org"
+                && url == "http://www.matrix.org"
+        );
+    }
+}