The purpose of the study was to determine the effectiveness of an exemplary science program in grades six, seven, and eight in developing (1) pupil understanding of basic facts, concepts, and principles of science and (2) pupil understanding about scientists, the scientific enterprise, the methods and aims of science as compared to the traditional programs ordinarily being taught at these grade levels. The study population consisted of 1,041 students in 54 sixth-, seventh-, and eighth-grade classes. Grade level, type of science course taught (traditional or the exemplary program), participation in elementary school science development projects, or not, and type of classroom set-up (departmental or self-contained) were considered. The Sequential Test of Educational Progress: Science, Forms 4A and 3A, and the Test on Understanding Science, Form Em, were administered as pre- and posttests. The Otis Quick-Scoring Mental Ability Test, Form Beta was used to control for academic aptitude. The t-test was used to determine for significant differences between pre- and posttest mean scores in achievement and understanding. A questionnaire was used to obtain teacher educational characteristics pertinent to the study. Data indicated that the teachers in schools participating in the treatment program planned to utilize a markedly greater amount of time for science instruction as well as having better educational backgrounds in science courses and science teaching (methods) courses. A very significant mean gain in achievement in science was demonstrated by the treatment group of students. (Author/EB)