This paper reviews research on effective pull-out programs for elementary students who are at risk for school failure. The emphasis is on programs that can be readily replicated by schools other than those that developed them. The focus is on programs provided to students who have been identified as in need of remedial services which are implemented outside of the regular classroom. The study found that effective pull-out programs for students fall into three broad categories: (1) diagnostic-prescriptive programs; (2) tutoring programs; and (3) computer-assisted instruction. Successful examples of each of these types are described and discussed. The most successful models completely adapt instruction to students' unique needs and provide plentiful direct instruction appropriate to their levels of readiness. Results of the study suggest that the achievement of at-risk students can be significantly increased, either by making relatively inexpensive but extensive modifications in the regular instructional program or by implementing relatively expensive but intensive interventions as pull-out programs. It is possible that a combination of these strategies would be more effective than either one by itself. An extensive list of references is included, along with descriptions of successful programs among each of the three types. (PS)