"Data Trends" reports present summaries of research on mental health services for children and adolescents and their families. The article summarized in this "Data Trends" is an analysis of secondary data obtained from a sample of 9 to 11 year old children receiving outpatient public mental health services in Philadelphia. The researchers hypothesized that participation in youth development activities would be associated with "such factors as family resources, child functioning, and family functioning." Although, in principle, positive youth development philosophy and programming are included in community-based approaches to improving mental health care for children, there is an absence of research that directly examines the integration of structured recreational activities into services. Overall, the authors of this study conclude that children receiving mental health services participate in structured activities at a level comparable to that of a nationally representative sample of youth. However, there is evidence that externalizing problems may be a barrier for some children, particularly if their adult caregivers have less education themselves. As the authors discuss, additional research that includes more complex measures of participation, such as frequency, intensity, and duration, is required to clarify these findings. The researchers also discuss ways of building more inclusive programs. This may require additional resources so that programs are better prepared to support children with disruptive behaviors and to accommodate the varied needs of families, such as inflexible work demands. Outreach to families with a history of unsuccessful educational experiences may be important in improving participation for some children. Individualized planning and youth and family involvement will be essential in learning how programs can be designed to maximize opportunities for positive youth development and for testing the outcomes for children with mental health difficulties. (Contains 1 table.) [This "Data Trends" presents a summary of: Keller, T. E., Bost, N. S., Lock, E. D., & Marcenko, M. O. (2005). Factors associated with participation of children with mental health problems in structured youth development programs. "Journal of Emotional and Behavioral Disorders," 13, 3, 141-151.]