This FLEX guide to researching labour exploitation sets out our approach to research with hard-to-reach migrant workers. In this guide, FLEX draws on insights from academic literature and experts in methodological approaches to engaging hard-to- reach groups in research. We discuss the advantages and challenges of the migrant community model and introduce practical tools developed for migrant community research. The guide is based on a FLEX pilot and we hope it can be a support to migrant and community organisations, trade unions and others engaging in similar projects.