This paper introduces a measure of continuity of care (CONNECT) developed for mental health services research. CONNECT addresses qualities of interpersonal interaction in service-user/practitioner relationships through 13 scales and one single-item indicator. The scales are grouped into five domains: knowledge, flexibility, availability, coordination, and transitions. Domains were derived from ethnographic data. Service users rate responses to items using 5-point scales The measure is administered in interview format. CONNECT was developed for use with persons who have serious mental illness. Preliminary testing included cognitive interviews and two pilot studies. The results of a field test in which 400 persons with serious mental illness completed CONNECT indicate that the measure is easily administered and produces well-distributed responses. Five scales meet the .80 criterion for internal-consistency reliability for group-level research. Estimates of 2-week test-retest reliability indicate fair-to-good agreement. A broad initial validation strategy including known groups and convergent validity assessments produced results that will inform and focus future efforts. Next steps in the measure development process are discussed.