Effects of a computerized professional development (PD) program for a concept teaching routine were investigated in two studies. For each, 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. In Study 1, the teachers' knowledge about the routine and planning for the routine significantly improved after completing either workshop; no significant differences were found between the groups. Both teacher groups were satisfied with the PD. In Study 2, the teachers' performance of the routine in their classrooms improved, as did student performance on tests of concept knowledge. Students were satisfied with the instruction provided by both groups of teachers. No differences were found between the posttest scores earned by the teacher groups or by students of the teachers. Implications regarding computerized PD for teachers are discussed. (Contains 2 figures and 1 note.)