Much of the reform rhetoric about professional development is geared toward the form that such development should take. This monograph advocates collaboration among teachers, schoolwide participation in professional development, programs that extend over time and are interspersed with classroom practice, and programs that include classroom visitations. Much less has been said about what the content of such programs should be. This paper reviews studies of inservice programs that aim to enhance mathematics and science teaching. It focuses exclusively on studies that examine the effects of these programs on student learning. The review suggests that the differences between programs that mattered most were differences in the content that was actually provided to teachers, not differences in program formats or structures. Contents include: (1) "Introduction"; (2) "The Literature"; (3) "Programs Aimed at Improving Student Learning in Mathematics"; (4) "Programs Aimed at Improving Student Learning in Science"; (5) "The Relevance of Other Features on Inservice Programs"; and (6) "Summary and Conclusions". (Contains 17 references.) (Author/YDS)