This study focuses on the effect of having a first child on parents’ criminal behaviour. First we examine whether after accounting for stable between person differences, such a parenthood-effect still exists. Next we examine whether this effect differs for men and women, having a child in or outside of wedlock or having a child at a young or average age. This study is based on the individual criminal careers of 3,527 men en 339 women. A fixed effects model was used to control for selection into parenthood and crime. Results show that criminal behaviour declines after having a first child among men, but that having a first child has no effect on women’s criminal behaviour. The independent effect of having a child is larger among unmarried men than married men. When men have their first child at a young age, however, their participation in crime increases.