The evaluation of social programs is typically hampered by serious methodological problems. Adopting the approach of Bayesian simultaneous estimation proposed by Lindley and Smith (1972) and operationally developed by Jackson, Novick, and Thayer (1971), Novick, Lewis, and Jackson (1973), and Lewis, Wang, and Novick (1975), we demonstrate how some of these problems can be avoided or solved. To accomplish this, we extend the operational method to marginalm-group mean analysis for the unbalanced case. Data from the Emergency School Aid Act (ESAA) evaluation are used for illustration. Bayesianm-group analysis techniques are applied to data gathered from 17 school districts to evaluate the effectiveness of each district's compensatory education program.