The purpose of this study was to directly observe and investigate the factors that support or hinder the implementation of an integrated approach to formative assessment and to understand how the implementation of formative assessment strategies interact. The authors present findings from a collective case study that included the observation of six teachers (three mathematics and three English language arts) who were purposefully sampled from a large, public, suburban high school in the northeast United States. The analysis of the case studies resulted in the identification of different patterns in teachers' formative assessment practice. These patterns illustrate how the complex interaction between formative assessment practices can either support or hinder the implementation of an integrated approach to formative assessment and suggests classroom observations as a potential mechanism for identifying challenges and informing just-in-time professional development.