Anxiety disorders are the most common mental health problems in children and teens. Worries and fears are a normal part of a child’s development, but should not be excessive, interfere with functioning, or persist beyond developmentally appropriate periods. Youth with anxiety disorders experience severe and persistent distress that interferes with their daily functioning in school and in social interactions, affecting the child’s cognition, emotional regulation and behavior. Anxiety disorders are often comorbid with depression, bipolar, obsessive-compulsive, learning/language, eating, attention-deficit/hyperactivity disorder (ADHD), and substance related disorders. Children and teens with obsessive-compulsive disorder (OCD) have obsessions, compulsions or both, which are time-consuming and cause clinically significant distress or impairment in social, occupational or other areas of functioning. Routine mental health screening is recommended at all well-child visits and for presentation of symptoms or concerns. This chapter reviews evidence-based assessment and management of anxiety disorders and obsessive-compulsive disorder.