Study aim: The general objective of this study is to assess and compare the effectiveness of transdiagnostic cognitive-behavioral therapy and mindfulness-based therapy in mitigating symptom severity related to attention deficit and hyperactivity/impulsivity. Additionally, we aim to address comorbid issues such as anxiety, depression, and emotional dysregulation among adolescents diagnosed with attention deficit hyperactivity disorder (ADHD). Design: A parallel-group, randomized clinical trial will be conducted, involving 30 patients. Randomization will be achieved using a table of random numbers, and blinding procedures will be implemented. Settings and conduct: Following participant selection and randomization, this study will be conducted at the Imam Khomeini Clinic in Tabriz. Blinding procedures will be implemented for participants, outcome assessors, and the individual responsible for statistical data analysis. Participants/Inclusion and exclusion criteria: Inclusion criteria: 1. Being diagnosed with ADHD disorder 2. Being in the age range of 14 to 17 years 3. Receiving a fixed dose of medicine from at least one month before the start of the study Non-inclusion criteria: 1. being diagnoesd with bipolar mood disorder 2. being diagnosed with psychotic disorders 3. being diagnosed with substance use disorder 4. Having serious suicidal thoughts 5. being diagnosed with conduct disorder Intervention groups: First Intervention Group: Participants in this group will receive transdiagnostic cognitive-behavioral therapy (TCBT) over 20 sessions, each lasting 45 minutes. Second Intervention Group: Participants in this group will undergo mindfulness-based therapy (MBT) for 20 sessions, with each session also lasting 45 minutes. Main outcome variables: symptoms of attention deficit and hyperactivity/impulsivity; severity of anxiety; severity of depression; Severity of emotional dysregulation