Peer assessment is a rather marginalised method in political research. This research note argues that the collective expertise of MPs can complement other data to contribute to more comprehensive evaluations of MPs’ parliamentary work. Yet, this method is potentially flawed by low survey participation and rater bias among MPs. The experience with a peer assessment survey among members of three Belgian parliaments shows that participation does not necessarily need to be problematic. However, the empirical analysis suggests that scholars should control for various forms of rater bias.