Follow Through is a longitudinal program instituted by the U.S. Office of Education in which a variety of curriculum models have been implemented in a number of locations nationwide. Because services are provided from kindergarten through third grade, many children enter and leave the program at points not coterminous with the treatment itself. The purpose of this study was to assess the effects of attrition on the national Follow Through evaluation. Relationships between child characteristics such as ethnicity, sex, family income, and mother's education and attrition group membership were investigated to determine whether the findings of the major analysis should be qualified. (Author)