Achievement in science depends among other factors on hypothetico-deductive reasoning ability; that is, on the developmental level of the students. Recent research indicates that developmental level of the students should be studied along with individual difference variables such as Pascual-Leone's M-capacity (information processing) and Witkin's Cognitive Style (disembedding ability). The purpose of this study was to investigate reasoning strategies of students in solving chemistry problems as a function of developmental level, functional M-capacity, and disembedding ability. A sample of freshman students (n=109) were administered tests of formal operational reasoning, functional M-capacity, disembedding ability, and chemistry problems (limiting reagent, mole, and gas laws). Results show that students who scored higher on cognitive predictor variables not only have a better chance of solving chemistry problems but also demonstrated greater understanding and used reasoning strategies indicative of explicit problem solving procedures based on the hypothetico-deductive method, manipulation of essential information and sensitivity to misleading information. It was also observed that students who score higher on cognitive predictor variables tend to anticipate important aspects of the problem situation by constructing general figurative and operative models leading to a greater understanding. Students scoring low on cognitive predictor variables tended to circumvent cognitively more demanding strategies and adopt others that helped them to overcome the constraints of formal reasoning, information processing, and disembedding ability. (Contains an annotated bibliography of 50 references.) (Author)