A quantitative review (meta-analysis) was undertaken to (1) synthesize existing evidence on the efficacy of joint mobilization and manipulation and (2) expose consumers of rehabilitation research to the methods and procedures of quantitative reviewing. Potentially relevant studies were obtained through a computer-assisted bibliographic search of the index Medicus data base and through examination of references contained in retrieved studies. A total of 57 titles were potentially relevant to manipulation/mobilization, but only nine met the prespecified criteria for inclusion in the quantitative review. Data analysis indicated that studies not employing random assignment were more likely to produce results supporting the use of manipulation/mobilization therapies. The effects in favor of manipulation and mobilization were greater when manual therapy was provided in conjunction with other forms of treatment and were also greater when the treatment effects were measured immediately following therapy. In addition, hypotheses tests appearing in journals published in the United States showed manipulation/mobilization less effective in comparison with reports appearing in English language journals published outside the United States. The results provided only limited empirical support for spinal mobilization and manipulation when used to treat pain, flexibility limitations, and impairment in physical activity.