Obsessive Compulsive Disorder is a debilitating disorder, which affects between 1 and 3% of young people; and has significant, long term, negative impacts on them and their families.  Currently the NICE recommended treatment for OCD in young people is Cognitive Behavioural Therapy (CBT) with parental involvement.  However no studies up until now have explicitly compared individual CBT for the child with CBT which includes parents.  A recent meta- analysis of psychological interventions for children and young people with anxiety disorders, including OCD, concluded that parental or family involvement in treatment did not improve treatment outcomes.  This seminar will focus on clinical and non-clinical research with young people and their families.  This includes observational and experimental data as well as data from the ROCKY Trial (Reducing Obsessions and Compulsions in Kids and Young People).  This trial compared the effectiveness of individual and parental enhanced CBT for OCD in young people age 12-18 years.  In addition young people and their parents were interviewed after treatment to assess the acceptability of both treatment arms and to identify key change mechanisms.  We also obtained ratings of the therapeutic alliance in both arms of treatment.  The data have clear implications for service delivery and treatment as well as indicating possible research directions.