Because of increased emphasis on accountability, program evaluations today must go beyond measures of change in program participants to consider the effects, either direct or indirect, of staff development on students and their learning. A model is presented illustrating the relationship between staff development for teachers and student learning outcomes, and the external factors that influence this relationship. Three factors are identified: (1) quality of the staff development program; (2) the content of the staff development program; and (3) the characteristics of the context in which the program is carried out. Although other models consider implementation as a separate factor, in this model quality or degree of implementation is considered a facet of the total process and therefore is a component of the first factor, the quality of the staff devlopment program. The potential effects of these factors on program evaluation results are described, along with procedures for estimating those effects. Finally, strategies are outlined, based on the model, for enhancing the quality and validity of staff development program evaluation. (IAH)