Educational programs and evaluations which were submitted to the Department of Education's Joint Dissemination Review Panel (JDRP), in order to be named validated programs, were studied to identify program characteristics associated with large versus small effect size. Effect size was calculated for 165 out of 232 submittals reviewed by JDRP from 1980 through 1983. Results indicated the largest variance in effect size was explained by content area (highest effect size in natural science and lowest in reading, language arts, and mathematics); and secondly, by reported annual operating funds (less than $100,000 had higher effect size). Other program characteristics related to large effect size were gifted participants, regular classroom setting, urban or suburban setting, and behavioral versus attitudinal or affective objectives. Lowest effect sizes were associated with handicapped audiences and special facilities. Locally developed tests, external evaluators, and randomized evaluation designs were associated with higher effect sizes. The combination of program and evaluation features which accounted for effect size were type of test, formula used to calculate effect size, type of objective, and evaluator affiliation. It was concluded that effect size data should not be interpreted simplistically; facile comparisons of the absolute values of effect sizes can tbe misleading. Several tables are provided. The appendixes consist of the JDRP Submittal Analysis Form as well as supplemental instructions for completing the form. (GDC)