This report focuses on the extent to which conclusions about the effectiveness of compensatory education programs are affected by (1) the period of time on which the evaluation is based, and (2) the standard against which the program is judged. Previously collected evaluation data from four compensatory education programs (grades 1-8) are reanalyzed in order to test the effects of these components. Program effectiveness is judged according to the standards of both grade-equivalent and percentile point achievement indices, as measured by standardized tests. The primary finding of these analyses is that conclusions about program effectiveness are greatly influenced by the the period of time over which the evaluation is based. Specifically, it is shown that the inclusion of the summer months in the evaluation can reduce estimates of achievement and reverse positive judgments of program effectiveness. Additionally, it is demonstrated that the 10 percentile point achievement standard is more stringent than grade-equivalent score standards, and is thus less likely to be met in a 12-month evaluation. Based on this study's findings, it is recommended that evaluation of compensatory programs be based on a 12-month (fall to fall) period and that students not be promoted on the basis of spring test scores. (Author/GC)