An Observation Guide, designed to help New Zealand teachers identify areas of teaching strength and aspects for development, was developed as part of a wider project. In the second phase of this project, 18 middle school teachers used the Guide to gather and record evidence as they participated in seven rounds of reciprocal peer observation and feedback during writing lessons with Grades 6-8 students. We report here on data from round 6 observations about the assessment for learning (AfL) strategies reported as evident in teachers' practices, how these strategies were implemented and potential gaps in practice. AfL has at its heart a core of interdependent strategies that collectively contribute to the development of autonomous, self-regulating learners and quality learning. While the middle school teachers shared goals for learning and communicated what counted as successful achievement to students, they appeared to struggle when articulating goals in terms of literacy learning and conveying the substantive aspects and quality expected in students' writing. In addition, despite AfL's promotion of learner autonomy, few teachers openly afforded students focused opportunities to take a meaningful role in their learning through the appraisal of their own and peers' writing and the joint construction of feedback. As such, teachers' AfL practice in the writing classroom failed to realise its full potential. It is argued that the promise of AfL can only be reached when strategies are enacted in ways that reflect its unitary nature, promote quality outcomes and give students a central role in their learning.