The present study tests the degree to which parents and children correspond in their reports on each others quantity and frequency of alcohol consumption. Furthermore, the degree of inaccurate estimation by parents might be related to inappropriate parenting. Particularly, parents who have little control over and knowledge of their offspring's activities and whereabouts might underestimate adolescent alcohol consumption. A full family design was employed in which both parents and two adolescents were included. A total of 428 Dutch families participated and filled in questionnaires at home in the presence of a trained interviewer on frequency and quantity of drinking. Findings showed that parents as well as children underestimate alcohol consumption of each other, in particular concerning the quantity of drinking. It appears that parents are better able to accurately estimate when their child is not drinking than when their child is drinking. Children on the other hand are better able to predict frequency and quantity of parental drinking, but not parental heavy drinking. Finally, parental underestimations of adolescent drinking are indeed related to lack of parental knowledge and control. However, this was primarily found among mothers. In conclusion, survey studies using collateral reports on parental and adolescent drinking should acknowledge the fact that in most cases family members underestimate alcohol consumption.