MPA is a structured method for obtaining and analyzing individual client data that have been collected by projects. Data from each project are examined and compared with other participating projects to identify similar data elements across data sets. Resulting data are then pooled where appropriate and analyses are conducted. The MPA approach is distinguished from cross-site evaluation; MPA represents an ad hoc effort without a common design, while cross-site evaluation is prospective with a common evaluation design and data elements across projects. The overall goal of MPA is to identify and assess what treatment interventions have the most beneficial impact on the following targeted populations: racial and ethnic minorities, adolescents, public housing residents and homeless persons, rural and migrant persons, and women and their children. Detailed findings on drug abuse among these populations and treatment services are summarized and tabulated. 24 figures