College instruction aims not only to expand students' content knowledge, but also to help students develop practical skills, such as the ability to think critically. This study was conducted in a chemistry course for non science majors offered as part of a liberal education core curriculum at a large public university in the Midwest. Students enrolled in the class were given the Lawson Classroom Test of Scientific Reasoning as a pre-and post-course measure of their scientific reasoning (SR) ability, a subset of critical thinking. Although average gains in student's SR ability were significant, the improvement was quite modest when compared with where students should be developmentally, according to Piaget. Literature suggests the need for instruction that markedly improves intellectual development, which may be attained through the use of more student-centered practices. Data presented support this need for instruction. (Contains 1 table and 12 figures.)