Validated tools are lacking in languages such as French to diagnose attention deficit hyperactivity disorder (ADHD) in adults. The Adult ADHD Symptoms Self-Report (ASRS) was filled out by 1171 parents of 900 school-aged youths in the context of the Children and Parents With ADHD and Related Disorders study. Prevalence estimates based on three scoring methods are compared (6-item screener, all 18 items, or the screener followed by the 12 remaining items). On the basis of the recommended and more conservative scoring method, the overall prevalence of ADHD symptoms is estimated to be 2.99%, without significant group differences between sexes or between younger and older adults. Potential correlates of ADHD symptoms were also examined in their relatives (children, brothers/sisters, uncles/aunts, and parents) as follows: birth order, level of education, body mass index categories, enuresis, suicide attempts, depression, and learning disabilities. Adults can be screened for ADHD symptoms using the ASRS; negative long-term outcomes should be assessed in patients' relatives too.