In managing treatment for persons with mental illness, the primary care physician (PCP) needs to communicate with mental health (MH) professionals in various settings over time to provide appropriate management and continuity of care. However, effective communication between PCPs and MH specialists is often poor. The present study reviewed evidence on the quality of information transfer between PCPs and specialist MH providers for referral requests and after inpatient discharge. Twenty-three audit studies were identified that assessed the quality of content and nine that assessed strategies to improve quality. Results indicated that rates of item reporting were variable. Within the limited evidence on interventions to improve quality, use of structured forms showed positive results. Follow-up work can identify a minimum set of items to include in information transfers, along with item definitions and structures for holding this information. Then, methodologies for measuring data quality, including electronically generated performance metrics, can be developed.