The scientific focus of criminological research has since long been on criminal and antisocial behaviour. However, a group of individuals reporting that they have never engaged in delinquent behaviour (delinquency abstainers) have consistently been identified and until only recently not rendered much scientific interest. It has by some been proposed that delinquency abstention is a result of individuals being excluded from peer groups due to undesired characteristics (e.g. high sense of moral beliefs), although this notion is contested. Morality has by others instead been perceived as having a direct effect on abstention, which is the hypothesis tested in this study. It does so by comparing delinquency abstainers to low- frequency non-abstainers with regards to moral belief, delinquent peer association, and time spent unsupervised with peers, and furthermore examines the effects across gender. Logistic regressions were run to examine direct and mediating effects using data from the longitudinal project Malmö Individual and Neighbourhood Developmental Study (MINDS). Results indicate that strong moral beliefs have a direct effect on abstention and that this effect is not mediated by delinquent peer association. Associating with delinquent peers did in turn predict non-abstention but spending time unsupervised with peers did neither predict abstention nor delinquency. Some gender differences found points towards stronger morality amongst females and that the effect of morality for males depends on peer association. Morality should therefore not be perceived as an undesirable characteristic which excludes individuals from peer groups but rather as an important factor in the inhibition of delinquency.