Classroom assessment in mathematics involves more than designing and grading summative assessments such as quizzes and tests. The methods teachers use during instruction to solicit evidence of student understanding are critical to effective formative assessment. Eliciting such evidence requires dynamic forms of discourse based, instructionally embedded assessment that reveal the connectedness and flexibility of student knowledge. Using semi-structured interviews, daily participant observation, and videotape of classroom instruction, this study documented ways in which middle grades mathematics teachers used instructionally embedded assessment to make judgments about student learning and inform instructional decisions. Through analyses of the teachers'' practices, two prerequisites and five techniques were identified regarding teachers use of instructionally embedded assessment.