Compared was the effectiveness of a two-year integrated chemistry-physics course with a two-year sequence of separate courses, in developing understanding of chemistry and physics concepts, understanding science and its methods, and reactions to the study of science. Both groups used the content, materials and instructional approach of the Chemical Education Materials Study (CHEMS) and the Physical Science Study Committee (PSSC) programs, but the integrated course was organized to eliminate overlap, show interrelatedness, permit more logical development of concepts, and allow opportunity for integration of the two disciplines. Significant differences favored the experimental group on knowledge achievement and application of physics and chemistry principles, but significant differences were not obtained on the "Test On Understanding Science." Differences detected were due to greater retention of chemistry concepts and better understanding of certain highly interdependent physics-chemistry concepts. (GR)