This paper contributes to the literature on participation and marginality on the geoweb by exploring the politics of non-mapping on OpenStreetMap (OSM). To this end, we reflect on our collaboration with Grassroots Jerusalem (GJ) – a Jerusalem-based Palestinian non-governmental organization (NGO) – and their engagement with OSM. Specifically, we draw on observations from mapping workshops with Palestinian youth, and on the analysis of GJ’s involvement in the dispute about the name ‘Jerusalem’ on OSM. We address the following research questions: How should we understand Palestinian underrepresentation on OpenStreetMap? What does this imply for the conceptualisation of participation and marginality in the geoweb literature? We suggest that the underrepresentation of Palestinian mappers stems in part from the project’s technical and linguistic barriers, and in part from a deliberate ‘exit’ tactic linked to Palestinian anti-normalisation efforts. These findings challenge prevailing understandings of (non)participation as the product of exclusion alone, and indicate that geoweb scholars should pay greater attention to non-users, and their engagements with crowdsourced projects from an outsider position.