Computerized science simulations were employed by high school biology students in an attempt to enhance their problem-solving skills. The simulations were administered under unguided (discovery learning) and guided (guided discovery learning) conditions while a control group received no simulations. To ascertain the effectiveness of the simulations in enhancing problem-solving abilities, performance was compared on: (1) subsequent unit pretests; (2) standardized tests measuring scientific thought processes; and (3) a standardized test of critical thinking. Results indicate that the students using the simulations met the unit objectives at least as well as the control students. In addition, students using the guided version of the simulations surpassed the other students on the subsequent simulation pretests, on the tests of scientific thinking, and on the test of critical thinking. In most cases, students using the guided version of the simulations developed these generalized skills more effectively than those using an unguided version. These results suggest that the computerized simulations can help high school students substantially increase their problem-solving abilities. However, to be most effective, it appears that the simulations should be integrated with curriculum objectives and should provide guidance to direct students to use the simulations efficiently. (Author/JN)