Reported is a study on the problem-solving skills of sixth-grade students. Three curricula were utilized in the study: Science - A Process Approach (SAPA), the Laidlaw textbook series, and the Environmental Studies (ES) Project materials. Twenty-seven teachers in eight schools participated. Each of the teachers taught one of the three curricula. The TAB Science Puzzler Form B was administered as a pretest and Form C, as posttest. The data were analyzed by an analysis of covariance technique. Pretest scores were used as the covariant and the posttest scores as the dependent variable. No differences was found in the improvement of certain selected problem-solving skills of students exposed to the Laidlaw science curriculum as compared to those having had the SAPA curriculum, but there was a difference with those using the ES program. A significant difference was found between the SAPA group as compared with a group using the ES program. Significant improvement of certain problem-solving skills was attained in both the SAPA program and in the textbook series. (Author/EB)