The present study examines whether perceived parental cultural socialization (e.g., encouraging cultural practices, traditions, language and cultural pride) is negatively associated with externalizing problem behaviours (e.g., fighting, expression of anger, lying and stealing) among Turkish-Dutch (n = 143) and Moroccan-Dutch (n = 164) youth (age 14–18), with ethnic in-group connectedness as a mediator. The results show that Turkish-Dutch youth, who report more cultural socialization efforts by their parents, are less likely to exhibit externalizing behaviours, because of their increased connectedness to the ethnic in-group. For Moroccan-Dutch youth, however, in-group connectedness is lower and we find no indirect effect of perceived parental cultural socialization on externalizing behaviours. We conclude that Turkish-Dutch youth seem to reap mental health benefits from what they perceive as their parents’ cultural socialization efforts. Thus, it is important to study ethnic differences in parental cultural socialization to enhance youth development across diverse youth populations in Europe.