Over the past two decades, due to the rapid increase in the number diagnosed with Attention Deficit Hyperactivity Disorder (ADHD), among both children and adults, questions have been raised regarding the related costs. What are the costs to individuals with ADHD and, more broadly, what are the costs to society? The purpose of this study paper - based on research conducted in Denmark - is to examine and answer these questions by estimating costs related to a long list of indicators in the course of an individual's life: educational attainment, occupational status, income, family situation, criminal record, health, etc. (Series: The Rockwool Foundation Research Unit - Study Paper - No. 69) [Subject: Sociology, Health Care, Danish Studies].