The overview of theoretical issues focuses on variability and constraints in treatment settings, variability among clinical syndromes, multidimensional problems, multiple outcome constructs, and temporal factors in the course of recovery. The section on technical challenges considers measurement reliability and resolution, standardization, and the feasibility of matching. Overall, the authors conclude that progress has been made in clarifying treatment matching variables, and field trials of placement-matching instruments are underway. Early results indicate that comprehensive placement criteria can be constructed with adequate reliability, feasible administration, concurrent validity, and a promise of outcome validity that will require field-trial completion. Problems remain to be solved, however, including patient acceptance, program flexibility, program characterization, service range expansion, managed care requirements, and special population placement matching. 72 references