A systematic look at four large staff development efforts, their staff development activities, their commonalities and differences, and their strengths and weakness focuses on the following programs: The New Teachers Workshop; Staff Development Program in Mathematics, Science and Computer Science; The Mentor Teacher Internship Program; and the Mathematics and Science Relicensing Project. The study describes the population served, selection criteria, the particpants' reactions to the training, the impact of the training on participants' performance in the classroom; the activities/practices that were successful; and the activities/practices that were not successful. Evaluation instruments consisted of an examination of existing program documentation, interviews of program participants and their supervisors, interviews with central program administration, analyses of participants' surveys, analyses of supervisors' surveys, and analyses of staff development reaction forms. Results showed that although these four programs addressed different teachers' needs in a variety of ways, the most successful activities/practices were those that delivered training in a timely fashion; matched training to the actual needs of teachers; scheduled staff development activities at convenient times in convenient locations; emphasized hands-on practical activities, techniques, and materials; provided additional avenues for learning beyond the training activities; provided incentives for participating teachers; piloted new staff development efforts on a small scale; and provided time for participants to share information and experience. Recommendations for strengthening each program are also offered. (JAM)