One or more non-transitory computer-readable media storing computer-executable instructions that, when executed by a processor, perform a method of presenting a user interface for synchronous multimedia collaboration in a group-based communication system, the method comprising: displaying, in the user interface for the group-based communication system, asynchronous message data in a channel-specific message pane associated with a channel of the group-based communication system; responsive to receiving, from a user of the group-based communication system and via the user interface, an instruction to initiate a synchronous multimedia collaboration session: automatically establishing the synchronous multimedia collaboration session between a plurality of participants, the participants being members of the channel of the group-based communication system; the method being characterized in further comprising: updating an indication in the channel-specific message pane of the user interface of the group-based communication system to indicate that the synchronous multimedia collaboration session is active, wherein the participants can leave and join the synchronous multimedia collaboration session without disrupting the synchronous multimedia collaboration session; displaying a synchronous collaboration pane in the user interface for the group-based communication system, the synchronous collaboration pane displaying a plurality of participating and non-participating channel members in the synchronous multimedia collaboration session and a status for each of the plurality of channel members; receiving a selection, from the user and via the user interface, of a new channel, the new channel being distinct from the channel; displaying data associate with the new channel in the channel-specific message pane; and in response to receiving a second instruction to initiate a second synchronous multimedia collaboration session: joining the second synchronous multimedia collaboration session associated with the new channel. displaying, in the user interface for the group-based communication system, asynchronous message data in a channel-specific message pane associated with a channel of the group-based communication system; responsive to receiving, from a user of the group-based communication system and via the user interface, an instruction to initiate a synchronous multimedia collaboration session: automatically establishing the synchronous multimedia collaboration session between a plurality of participants, the participants being members of the channel of the group-based communication system; the method being characterized in further comprising: updating an indication in the channel-specific message pane of the user interface of the group-based communication system to indicate that the synchronous multimedia collaboration session is active, wherein the participants can leave and join the synchronous multimedia collaboration session without disrupting the synchronous multimedia collaboration session; displaying a synchronous collaboration pane in the user interface for the group-based communication system, the synchronous collaboration pane displaying a plurality of participating and non-participating channel members in the synchronous multimedia collaboration session and a status for each of the plurality of channel members; receiving a selection, from the user and via the user interface, of a new channel, the new channel being distinct from the channel; displaying data associate with the new channel in the channel-specific message pane; and in response to receiving a second instruction to initiate a second synchronous multimedia collaboration session: joining the second synchronous multimedia collaboration session associated with the new channel. automatically establishing the synchronous multimedia collaboration session between a plurality of participants, the participants being members of the channel of the group-based communication system; the method being characterized in further comprising: updating an indication in the channel-specific message pane of the user interface of the group-based communication system to indicate that the synchronous multimedia collaboration session is active, wherein the participants can leave and join the synchronous multimedia collaboration session without disrupting the synchronous multimedia collaboration session; displaying a synchronous collaboration pane in the user interface for the group-based communication system, the synchronous collaboration pane displaying a plurality of participating and non-participating channel members in the synchronous multimedia collaboration session and a status for each of the plurality of channel members; receiving a selection, from the user and via the user interface, of a new channel, the new channel being distinct from the channel; displaying data associate with the new channel in the channel-specific message pane; and in response to receiving a second instruction to initiate a second synchronous multimedia collaboration session: joining the second synchronous multimedia collaboration session associated with the new channel.