Since publication of the Coleman Report, the belief has become increasingly pervasive that formal education does not or cannot make a difference in what a student learns--that patterns of academic performance are immutably molded by social and economic conditions outside the school. The purpose of this paper is to present a comprehensive review and analysis of 19 school effectiveness studies. The four-section paper (1) attempts to place contemporary assessment efforts in historical perspective; (2) discusses the nature and limitations of such studies; (3) presents a study-by-study review of recent efforts to examine systematically the impact of school variables upon student performance; and (4) summarizes the school service components which were consistently found to be significantly associated with one or more measures of pupil performance (i.e., the number and quality of professional staff, particularly teachers; contact frequency with professional staff; adequacy and extent of physical facilities for instruction; and expenditures per pupil and teacher). The amount and consistency of evidence supporting the effectiveness of school services in influencing academic performance lead to the conclusion that although there is a need for more precise information about which components are most effective and in what mix or proportion they can be made more effective, there can be little doubt that schools do make a difference. (Also included: a summary chart which condenses the essential components of each investigation and a 38-item list of references.) (JES)