The Iowa Chautauqua Program has provided effective staff development for over 2,700 K-12 science teachers during the past two decades. This is a review of the features of the program, its instructional staff, and a description of the outcomes as disclosed from evaluative studies conducted by staff, teacher participants, doctoral students, and outside evaluators. Examples of outcomes are included as revealed from the qualitative studies reported in newsletters, published papers, dissertations, annual staff reports, and evidences of success reported to accrediting groups. The Chautauqua stresses student-centeredness, constructivist learning, and the visions of reform featured in the National Science Education Standards.