Data from the National Education Longitudinal Study of 1988 (NELS:88) and the Hopkins Enhancement Survey of NELS:88 Middle Grades Practices were used to examine the prevalence and antecedents of different types of remedial activities in the middle grades. Data were also used to estimate the effects of remedial activities on the mathematics and reading achievement of public school students who had fallen behind in school. Usable data were obtained from over 1,000 schools. Results indicated that pull-out programs, after- or before-school coaching classes, peer tutoring, and summer classes were the most common types of remedial activity. The probability of a school offering a particular type of remedial activity was moderately dependent on the school's geographic region, the socioeconomic characteristics of the student population, and whether the school was public or private. Remedial activities that provided students with substantial extra instruction were effective in raising achievement test scores. Peer tutoring, and before- or after-school classes, were not effective in raising test scores. A list of 13 references is provided. (BC)