This paper traces the design, development and trialling of an assessment for learning audit instrument (AfLAi) in use currently in the Republic of Ireland to gauge teachers’ baseline understanding of AfL practices and the extent to which AfL is embedded in their teaching. As described in the paper, the AfLAi consists of 58 items distributed across four scales based on the following key AfL strategies: sharing learning intentions and success criteria, questioning and classroom discussion, feedback, and peer- and –self ssessment. Preliminary data from the study provide a window into current formative assessment practices in Irish primary schools and teachers’ professional needs in AfL.