This study analyzed three different middle school mathematics formative assessment programs, examining how features of each program were associated with the information they provided to teachers and the manner in which teachers used the information. The research team found considerable variation in the information teachers obtained from each program and how they used it. They found that greater familiarity with the specific formative assessment system did seem to be accompanied by more integrated use during the school year. They also found that teachers seemed to find it easier to incorporate the systems that had pre-existing assessments than the system that put the burden for assessment design on their shoulders. The results from this study can aide teachers, administrators and other education stakeholders in deciding which formative assessment systems to adopt, planning for the implementation of formative assessment and providing adequate training for teachers, designing formative assessment systems that better meet teachers' needs, setting realistic expectations for the impact of formative assessment systems on a large scale, and lastly, understanding the impact of formative assessment in a particular context. Appended are: (1) The CRESST Project on Interim and Formative Assessment; (2) Reporting Template--Communal Grading of Noyce Assessments. (Contains 4 figures, 1 table and 5 footnotes.)