The purpose of the two studies reported in this article was to measure the effects of a computerized professional development program for a concept teaching routine. For each study, teachers were randomly assigned to either a virtual workshop group that used a multimedia software program for PD or an actual workshop group that participated in a live PD session. These two studies demonstrate that computerized professional development programs can be designed in ways that teachers gain a great deal of knowledge about an instructional practice and express high levels of satisfaction with what they have learned and how they have learned it.