The aims of this study were (a) to investigate sex differences in risk factors for re-offending and (b) to provide a risk assessment model for girls. The data of 1,396 adolescents who committed a criminal offense were examined. Both generic and sex-specific risk factors for re-offending were found. The girl-specific risk factors are located mainly in the family domain. These girl-specific risk factors turn out to be by far the most important predictors for re-offending for girls. The risk assessment model divides girls into four different risk groups: a low risk group (containing 65% of the girls) and three high risk groups (girls with delinquent parents, victims of abuse, and repeat offenders), each showing a specific set of risk factors, which suggests the need for specific interventions.