The purpose of the study was to examine the effectiveness of the Chautauqua Professional Development Program in terms of the mastery of basic science concepts, understanding major science processes, use of creativity skills, improvement of student attitudes toward science, and the ability to apply science concepts and processes in new situations. Participants included twelve teachers who agreed to participate in an experimental study where Science, Technology, and Society (STS) strategies were utilized with two class sections where in one class the teacher determined the course structure and the form of instruction that was typically used. Conversely, the experimental class was almost exclusively student-centered. A total of twenty-four sections of students were in STS sections (365 students) and a similar number in control sections (359 students).The data collected were analyzed using quantitative methods. The results were tabulated and contrasted for students enrolled in the two sections for all the teachers. The results indicate that students in the student-centered STS sections achieved significantly better than students in the teacher-directed STS sections in terms of understanding and use of process skills, use of creativity skills, development of more positive attitudes; and the ability to apply science concepts in new contexts. However, there were no significant differences noted with respect to mastery of basic science concepts. Apparently student-centered STS approaches result in students with conceptual understandings but it is no better than the situation where teachers guide and direct inquiry STS approaches which focus much more exclusively on specific concepts and their definitions.