Objectives: The interpretation of research findings based on self-reported delinquency requires knowledge of how response rates depend on the attributes of potential respondents, including their prior offending. The purpose of the present study was to quantify the extent to which, in a sample of offenders, the two main determinants of non-response, non-contact and refusal, depend on prior offending frequency. Methods: We used binomial and multinomial regression models to assess whether frequent offenders are more difficult to contact and less willing to participate in online surveys. These hypotheses are tested on a sample of offenders who were invited by regular mail to participate in the OASIS, an online survey on mobility and safety. Findings: Controlling for gender and age as potential confounders, our findings do not confirm that frequent offenders are less likely to be successfully contacted, but they do confirm that if contacted, they are less likely to participate. Conclusions: Response rates in offender-based research are selective and thus potentially biased towards infrequent offenders. They generally favor conservative estimates and conclusions, implying that any found associations between crime and its predictors are likely stronger in reality.