In the evaluation of educational programs, the context in which an intervention is being implemented greatly impacts its outcomes. Changes within an educational context that are relatively common, such as teacher turnover, a transient student population, or varying attitudes toward novel teaching strategies, have the potential to influence the determination of whether or not a program should continue. How does context, whether it is static or emerging, affect formative assessment, which involves teachers using evaluative skills and strategies to improve student learning? This paper will explore studies of the implementation of formative assessment in PreK-12 schools, and how the context in each study affected its perceived efficacy. Factors will be examined such as student demographics and ability levels, teachers' instructional strategies, and administrative support of formative assessment and its use in the classroom. Implications for the application of this research to formative evaluation and program evaluation will also be considered.#Prek-12EducationalEvaluation #2011Conference #YouthFocusedEvaluation