Scheme is similar to Common Lisp and C in that the language is based around a well-known standard with many implementations, and the people whose ideas begat the standard are no longer active around the language. Since the founders are gone, no-one has a natural right to own the communities around these languages, and several prominent sub-communities have formed.
The most official Scheme group is the Steering Committee, which approves revisions of the standard. The committee stays out of day-to-day affairs. In practice, the most representative Scheme communities gather around the major implementations, on the SRFI mailing lists, the #scheme IRC channel, the comp.lang.scheme newsgroup, and at the Scheme Workshop.
Stack Overflow (Scheme tag)
Rosetta Code (Scheme category)
Scheme Topics mailing lists (hosted at SRFI)
r/scheme on Reddit
IRC is most easily visited via webchat. For regular use, it's recommended to install an IRC client on your computer. For persistent sessions so you don't get logged out of IRC when shutting down your computer, an IRC client or a bouncer can be installed on a Linux or Unix server, and run as a background process on a shell account. Universities commonly provide a shell account suitable for IRC to their students and faculty. IRCCloud is a commercial bouncer with a webchat.
Scheme is a prominent member of the Lisp language family. Channels dealing with the family as a whole are included on this page.