Is your child between 9 to 17 years of age? Does your child have obsessive-compulsive disorder (OCD)? Do they have intrusive thoughts or pictures that come into their head and make them feel bad? Do they have to do things over and over again in order to make themselves feel better? If so, your child may be eligible to participate in a trial being conducted at the UCLA Child OCD Program. All eligible participants receive a free 12-week course of standard psychological treatment, known as exposure and response prevention (ERP). Participants will also be using a mobile application along with standard treatment for 6 of the 12 weeks to see if it may help enhance treatment. Interested families should contact us at (310) 825-0122 or e-mail Silvia Orellana at SilviaOrellana@mednet.ucla.edu.