The comorbidity of attention deficit hyperactivity disorder (ADHD) is frequently not well recognized in substance abuse treatment institutions in The Netherlands. As a consequence, patients with substance use disorder (SUD) and ADHD often receive suboptimal treatment. To prevent every treatment center from having to invent its own diagnostic procedure and intervention for ADHD, a national working group was established. This group developed an intervention program for the screening, diagnosis, and treatment of ADHD in patients with SUD. This article describes the development and content of this intervention program. An important part of this development was testing the intervention program in two addiction treatment centers in The Netherlands. Systematic screening of ADHD was part of the test. A self-report questionnaire was used. Subjects with positive screening results were referred for the diagnostic procedure. Nine hundred twenty-eight screenings were performed: 207 screened positive, 115 came for further diagnostics, and 65 were ultimately diagnosed with ADHD.