Few studies have examined the longitudinal impact that systems of care (SOCs) have on the clinical functioning of young people. This study investigated patterns of clinical improvement over time in an SOC and explored the degree to which demographic characteristics and referral source affected those patterns. Data were gathered at the time of enrollment in the SOC and collected at 6-month intervals, up to 36 months. Clinical change was assessed with three measurement tools, using hierarchical linear modeling to examine change patterns longitudinally. Results indicated that there were several clinical differences at the time of enrollment that were associated with specific demographic characteristics or referral source. Findings also indicated that clinically and statistically significant improvements occurred over time, with little regard to participants' demographic characteristics or source of referral. These findings lend support to the potential of SOCs to improve youth outcomes and suggest that such improvements appear regardless of individual-level differences among participants. (Contains 5 tables.)