This article argues that the engagement of teachers in collaborative discussions about assessment can provide a fruitful context for valuable professional learning. It is of interest to those who provide Continuous Professional Development (CPD) opportunities for teachers and teachers themselves. It looks particularly at the value of writing assessment moderation meetings, where teachers aim to use exemplars of pupil work to arrive at commonly held understandings about pupil achievement. Teachers' views of participating in the process of assessment moderation were sought. In the case study, two rounds of semi-structured interviews were conducted by the researcher with a project team of one staff tutor and six teachers. Data from these interviews were supplemented by field notes from the project team meetings and a one day writing assessment moderation meeting which was attended by teacher representatives from 10 schools. The results have implications for the organization of assessment moderation meetings within and between primary and secondary schools.