  A major goal for the astronomy and astrophysics communities is the pursuit of
diversity, equity, and inclusion (DEI) in all ranks, from students through
professional scientific researchers. Large scientific collaborations -
increasingly a primary place for both professional interactions and research
opportunities - can play an important role in the DEI effort. Multimessenger
astronomy, a new and growing field, is based on the principle that working
collaboratively produces synergies, enabling advances that would not be
possible without cooperation. The nascent Multimessenger Diversity Network
(MDN) is extending this collaborative approach to include DEI initiatives.
After we review of the current state of DEI in astronomy and astrophysics, we
describe the strategies the MDN is developing and disseminating to support and
increase DEI in the fields over the coming decade: provide opportunities (real
and virtual) to share DEI knowledge and resources, include DEI in
collaboration-level activities, including external reviews, and develop and
implement ways to recognize the DEI work of collaboration members.
