This study investigated the relationships among oppositional defiant attitudes, moral reasoning, moral value evaluation and self-reported delinquent behaviour in adolescents ("N" = 351, "M"[subscript AGE] = 13.8 years, "SD"[subscript AGE] = 1.1). Of particular interest were the moderating effects of age, educational environment and gender on the relationship between moral reasoning and delinquency. The results indicate that oppositional defiance was a strong positive correlate of delinquent behaviour, particularly in late adolescence. Furthermore, moral reasoning was modestly and negatively related to delinquency, but only for males. No moderating effects for educational environment were observed. Moreover, moral value evaluation was uncorrelated with delinquent behaviour when controlling for other sociomoral processes. These findings invite further research on the relationship between attitudes and behaviour, with respect to causal links and practical applications within behavioural interventions.