This study examined the impact of microcomputer simulations on environmental problem solving by community college students. A subordinate question was also addressed: Was the test instrument, which was used to assess the outcome of the treatment, biased by reading ability? The quasiexperimental design used two intact groups of community college students and parallels an earlier study by Rivers and Vockell (1987). The experimental group was assigned three simulation modules that focused on lake pollution analysis, wastewater quality management, and population dynamics. The comparison group was not exposed to any simulations, and served as a quasicontrol to identify possible Hawthorne effects. Effectiveness was assessed by the Test of Integrated Process Skills (TIPS I and II). Statistical analyses were done with t tests, Pearson product-moment correlation coefficients, and reliability coefficients. The experimental group showed a highly significant improvement in problem-solving skills after treatment, t(33) = 4.42, p < 0.001. Subtest mean gain scores supported the hierarchical relationships among cognitive modes for transitional operational reasoners as reported by Yap and Yeany (1988). An analysis of the correlation between the TIPS I and Nelson-Denny reading test scores indicated that the TIPS did not have a reading-level bias for the subjects in this study. Informal and anecdotal observations described improvements in other problem-solving skills which were not measured by the TIPS.