This observational study is a first orientation on the effects and feasibility of a group training to plan and organize for adolescents with attention deficit disorder (ADHD). This study focuses on the following questions:

• Is there an improvement on planning skills after training?
• Are there fewer ADHD characteristics after training?
• Is there an improvement on self-esteem after training?
• How feasible is a group training for adolescents with ADHD?
• How satisfied are practitioners and adolescents about the training?

Based on the effect-size of the individual training variant, the literature on the effect of group treatment and the adolescent target group, in which the peer group gets more important, the hypothesis is that the group training Plan My Life Together will have a medium to large effect on planning skills. Furthermore, positive effects on ADHD characteristics and self-esteem are also expected. The assumption is that Plan My Life Together is feasible and suitable.

Attention deficit and/or hyperactivity and impulsivity disorder (ADHD) has a high prevalence in the adolescence. In this age stage, where independence and personal responsibility become increasingly important, ADHD is characterized mainly by problems in executive functions and there are often problems in planning schoolwork.This is frequently accompanied by tensions in the family. More co-morbidity also develops, including problems in self-image, as a result of negative feedback from the environment. Individual behavioral treatment has been found to be effective in reducing ADHD symptoms. In the ADHD guidelines (cognitive) behavioral therapy aimed at planning and organization, with consideration for motivational interviewing elements, is recommended for adolescents.

In the individual training Plan My Life, adolescents learn to plan their school and homework better through cognitive behavioral therapy (CBT) and motivational interviewing, so that they have fewer problems with their ADHD characteristics and have more positive experiences. The training is proven effective, few adolescents drop out, and parents and practitioners are positive about the training. The training was developed and studied on an individual basis.

There may be advantages to offering this training in a group setting. Among other things, the group can serve as a catalyst and experiences can be shared. Group therapy has been shown to work for several mental disorders, in some cases even better than the individual therapy. It is obvious that in adolescence the group is relatively even more important. Also, group treatment can be more efficient.

Inclusion Criteria:

• adolescents with an ADHD classification according to the DSM-5.
• age 12 to 16 years.
• outpatient treatment at "GGZ-NHN" (specialized mental health care service in the Netherlands)) or at "Psychologenpraktijk Kuin" (first-line psychological mental health care, Haarlem)
• currently following secondary regular education
• Intention to participate in the group and willingness to fill out questionnaires several times.

Exclusion Criteria:

• a DSM-5 classification of autism
• acute crisis situation (acute suicidality, acute psychotic symptoms, addiction problems requiring immediate treatment, or unsafe home situation)
• Insufficient mastery of the Dutch language.

Participants are from the region "North-Holland" and receive mental health care for ADHD and possible other mental health problems. Medication use is allowed if participants function stable on medication.

Anonimized data will be shared upon request and careful consideration of research plan by the principal investigators.