This chapter provides an overview of several dimensions of research and program evaluation in school psychology. It reviews various evaluation models that can be employed in school service evaluation and discusses some types of research and program evaluation strategies that have been employed in school settings. The effectiveness of school psychological services continues to be a major concern in the field of psychology and education. Consultation is used as an example of how various research strategies are used to answer questions regarding the knowledge-base in an area of investigation. Consultation research was selected because it represents a prominent role function in school psychology, research has been conducted on various models or approaches to consultation and fundamental disagreement exists regarding the appropriate methodologies that should be used to evaluate consultation. The chapter concludes with some methodological and conceptual issues that have relevance to future research and practice in school psychology.