This study represents one of the first major summative evaluations of the Science Curriculum Improvement Study (SCIS), a federally funded, six-year elementary science program. An instrument was designed for measuring the effects of SCIS on the stated goal of the curriculum, the development of scientific literacy. Subjects were rural sixth-grade children: 312 had studied SCIS; 219 were otherwise comparable but had not studied SCIS. Results indicated that SCIS contributed to the development of scientific literacy. Specific tasks which differentiated SCIS from non-SCIS students included the identification and control of variables, understanding relative position, and explaining energy transfer. Regardless of SCIS experience, the girls outperformed the boys on the Scientific Literacy Test developed for this study. (Author/BW)