There is a critical need for high quality science (physics, physical science) teachers in the United States. We have developed an online course to help in-service teachers update their pedagogical and content knowledge about contemporary physics. Contemporary Physics Online adapts an existing on-campus course for Internet delivery. The course utilizes computer programs and hands-on activities to focus on 20th Century physics. Experiment kits are mailed to the teachers. These teachers also participate in a summer workshop after completion of the online component. We provide follow-up support to facilitate the development and transfer of new teaching materials into their classrooms.