This study was designed to assess the effect of a process oriented elementary science curriculum upon students' achievement. The Iowa Tests of Basic Skills (ITBS) Complete Battery with the social studies and science supplements was administered to sixth grade students completing one, two, or three years of the Science through Discovery program in the Richardson Independent School District, (Texas). The Comprehensive Test of Basic Skills (CTBS) which was administered to these students in the third grade was used as a covariate to control statistically for any pretreatment differences in achievement. The paper concluded that students exposed to process science for three years who only covered 42 percent of the test items performed as well as students who were exposed to 86 percent of the content assessed. Post hoc analyses were conducted using t-tests to examine the issue of gender equity or disparity as a function of the curriculum being implemented and/or test congruence. (Author/YP)