This study was designed to assess the effectiveness, with respect to science process skill development, of the elementary science curriculum designed by the Science Curriculum Improvement Study (SCIS). The assessment was made by statistically comparing the scores on "The Science Process Instrument" of two groups of students. The experimental group had only the SCIS program in learning science; the second group, the control group, used only the textbook approach to learning science. Data clearly indicated the superiority of the SCIS curriculum over the textbook curriculum for developing the student's ability to utilize science processes. (Author/CP)