The authors investigated the impact of professional development programs for English-as-a-second-language (ESL) teachers on their classroom practice and on the way that teacher efficacy and organizational support at the school level relate by interacting with years of teaching experience. The authors collected data by using questionnaires administered to 90 elementary and secondary teachers participating in ESL training programs. Results based on multiple-regression analyses indicated that teacher efficacy and organizational support significantly predict level of professional development impact without interacting with years of teaching experience. Appended are: (A) Modified Teacher Efficacy Scale; (B) Organizational Support Scale; (C) Impact Scale; and (D) Teacher Background Questionnaire. (Contains 4 tables.)