This study investigates the effect of being an outlaw biker on criminal involvement in Denmark. Using a unique dataset, 297 outlaw bikers are matched on various background characteristics with 181,931 control individuals and effects are estimated in difference-in-difference regressions. This approach reduces the risk of selection bias and helps isolate the effect of affiliation on criminal involvement. The results suggest that affiliation with an outlaw motorcycle club may increase involvement in overall crime, specifically property crime, drug crime, and weapons crime. Results regarding violent crimes are inconclusive. It is concluded that an outlaw biker affiliation may increase criminal involvement.