diff --git a/discord/guild.py b/discord/guild.py
index 25e7d402c..4e7e38f67 100644
--- a/discord/guild.py
+++ b/discord/guild.py
@@ -213,6 +213,11 @@ class Guild(Hashable):
     def _add_member(self, member):
         self._members[member.id] = member
 
+    def _store_thread(self, payload) -> Thread:
+        thread = Thread(guild=self, data=payload)
+        self._threads[thread.id] = thread
+        return thread
+
     def _remove_member(self, member):
         self._members.pop(member.id, None)
 
diff --git a/discord/state.py b/discord/state.py
index e9e4fa4d0..85a94cee9 100644
--- a/discord/state.py
+++ b/discord/state.py
@@ -28,6 +28,7 @@ import copy
 import datetime
 import itertools
 import logging
+from typing import Optional
 import weakref
 import warnings
 import inspect
@@ -56,6 +57,7 @@ from .interactions import Interaction
 from .ui.view import ViewStore
 from .stage_instance import StageInstance
 from .threads import Thread, ThreadMember
+from discord import guild
 
 class ChunkRequest:
     def __init__(self, guild_id, loop, resolver, *, cache=True):
@@ -724,7 +726,7 @@ class ConnectionState:
             return
 
         thread_id = int(data['id'])
-        thread = guild._get_thread(thread_id)
+        thread = guild.get_thread(thread_id)
         if thread is not None:
             old = copy.copy(thread)
             thread._update(data)
@@ -734,15 +736,56 @@ class ConnectionState:
         guild_id = int(data['guild_id'])
         guild = self._get_guild(guild_id)
         if guild is None:
-            log.debug('THREAD_UPDATE referencing an unknown guild ID: %s. Discarding', guild_id)
+            log.debug('THREAD_DELETE referencing an unknown guild ID: %s. Discarding', guild_id)
             return
 
         thread_id = int(data['id'])
-        thread = guild._get_thread(thread_id)
+        thread = guild.get_thread(thread_id)
         if thread is not None:
             guild._remove_thread(thread)
             self.dispatch('thread_delete', thread)
 
+    def parse_thread_list_sync(self, data):
+        guild_id = int(data['guild_id'])
+        guild: Optional[Guild] = self._get_guild(guild_id)
+        if guild is None:
+            log.debug('THREAD_LIST_SYNC referencing an unknown guild ID: %s. Discarding', guild_id)
+            return
+
+        threads = {
+            d['id']: guild._store_thread(d)
+            for d in data.get('threads', [])
+        }
+
+        for member in data.get('members', []):
+            try:
+                # note: member['id'] is the thread_id
+                thread = threads[member['id']]
+            except KeyError:
+                continue
+            else:
+                thread._add_member(ThreadMember(thread, member))
+
+        # TODO: dispatch?
+
+    def parse_thread_member_update(self, data):
+        guild_id = int(data['guild_id'])
+        guild: Optional[Guild] = self._get_guild(guild_id)
+        if guild is None:
+            log.debug('THREAD_MEMBER_UPDATE referencing an unknown guild ID: %s. Discarding', guild_id)
+            return
+
+        thread_id = int(data['id'])
+        thread = guild.get_thread(thread_id)
+        if thread is None:
+            log.debug('THREAD_MEMBER_UPDATE referencing an unknown thread ID: %s. Discarding', thread_id)
+            return
+
+        member = ThreadMember(thread, data)
+        thread._add_member(member)
+
+        # TODO: dispatch
+
     def parse_guild_member_add(self, data):
         guild = self._get_guild(int(data['guild_id']))
         if guild is None:
diff --git a/discord/threads.py b/discord/threads.py
index 6249aff8b..696b7495a 100644
--- a/discord/threads.py
+++ b/discord/threads.py
@@ -23,7 +23,8 @@ DEALINGS IN THE SOFTWARE.
 """
 
 from __future__ import annotations
-from typing import Optional, TYPE_CHECKING
+from discord.types.threads import ThreadMember
+from typing import Dict, Optional, TYPE_CHECKING
 
 from .mixins import Hashable
 from .abc import Messageable
@@ -117,6 +118,7 @@ class Thread(Messageable, Hashable):
         'guild',
         '_type',
         '_state',
+        '_members',
         'owner_id',
         'parent_id',
         'last_message_id',
@@ -134,6 +136,7 @@ class Thread(Messageable, Hashable):
     def __init__(self, *, guild: Guild, data: ThreadPayload):
         self._state: ConnectionState = guild._state
         self.guild = guild
+        self._members: Dict[int, ThreadMember] = {}
         self._from_data(data)
 
     async def _get_channel(self):
@@ -344,6 +347,9 @@ class Thread(Messageable, Hashable):
         """
         await self._state.http.delete_channel(self.id)
 
+    def _add_member(self, member: ThreadMember) -> None:
+        self._members[member.id] = member
+
 
 class ThreadMember(Hashable):
     """Represents a Discord thread member.