Despite their recent emergence, WhatsApp Neighbourhood Crime Prevention (WNCP) groups are an already pervasive phenomenon in the Netherlands. This study draws on interviews and focus groups in order to provide an in-depth multidimensional analysis of the watchfulness and surveillance activities within these groups. The conceptualisation of WNCP through the lens of practice theory shows that the use of ICTs in the form of WhatsApp amplified all three dimensions of neighbourhood watchfulness practices. It examines how friction at the intersections of materialities, competencies and meanings affect neighbourhood dynamics as well as the personal lives and experiences of people (who may be unknowingly) involved. While voluntary citizen participation in crime prevention leads to an increase in social support, feelings of safety, and the active prevention of break-ins, it also defaults to forms of lateral surveillance which transcend digital monitoring practices. Pressing issues related to social media use, participatory policing, surveillance, and the normalisation of distrust and intolerance have an impact beyond its localised Dutch context.