Background and Importance: Challenges in healthcare policy and practice have stimulated interest in dissemination and implementation science. The Institute of Medicine Committee on the Clinical Translational Science Award (CTSA) program recommended expanding the CTSA program's investment and activity in this domain. Guidance is needed to facilitate successful growth of DII science infrastructure, activity and impacts. Objectives: Several CTSAs in Southern California collaborated to identify and respond to local challenges and opportunities to expand dissemination, implementation and improvement research by strengthening capacity and relationships between DII researchers and community, health system, and population health partners. Main outcomes: Planning and outreach by the Southern California CTSAs increased awareness and interest in DII research and generated recommendations for growth. Recommendations include: increasing strong partnerships with healthcare and population health systems to guide policy research agendas and collaborative DII science; promoting multi-sector partnerships that involve researchers and delivery systems throughout DII processes; bringing together multiple disciplines; and addressing national and international barriers as well as opportunities in DII science. Implications: CTSAs through regional collaboration can increase their contributions to improved community health via skill-building, partnership development and enhanced outreach to local healthcare and public health agencies and delivery systems.