In this study, we examined the enactment of formative assessment by administrator-selected master teachers in large, urban, public school districts in three regions of the United States. Furthermore, this study also included an investigation of the perceptions and frequency of use for all teachers within the same districts to gather a snapshot of the state of use of formative assessment within those settings overall. Currently, the research base is limited regarding how effective teachers implement formative assessment strategies in their classrooms and how teachers in general perceive formative assessment. Thus, the purpose of this study was to gain a broader understanding of how teachers conceptualize and enact formative assessment strategies in their classrooms with the aim of providing guidance to teacher educators, professional development providers, and policy makers about gaps in teachers' understanding of and use of formative assessment. Findings from classroom observations revealed that master teachers implemented some aspects of formative assessment effectively and other areas were used much less frequently and/or effectively. Teachers within the participating districts reported similar use frequencies. Implications for research and practice in the area of formative assessment are discussed.