This study reports the results of a best-evidence synthesis of research on the use of one-to-one tutoring delivered by adults to students in the primary grades who are learning to read. The synthesis includes research on five programs: Reading Recovery, Success for All, Prevention of Learning Disabilities, the Wallach Tutorial Program, and Programmed Tutorial Reading. All five programs showed substantial positive effects on student reading achievement. Two studies found cumulative effects of one-to-one tutoring, and one found lasting but diminishing effects. The five programs showed substantially more positive effects on student reading achievement than did other programs with similar costs. Positive effects included reduction of class size and provision of aides to classes. In Table 1, characteristics of the programs are summarized in terms of the location of the evaluation, tutor qualifications, tutee characteristics, duration of intervention, and tutoring methods and curriculum. Thirty-five references are cited. (Author/RH)