Mental health/behavioral disorders have been increasing over recent decades and now affect approximately one out of five children and adolescents, creating a major public health epidemic. The three most common mental health problems in children and adolescents are anxiety disorders, depressive disorders, and attention-deficit/hyperactivity disorder with depression being the most costly primary mental health diagnosis. Early detection of and evidence-based intervention for mental health/behavioral problems is critical in order to prevent serious ongoing adverse outcomes. This chapter provides questionnaires that can be used for the purpose of collecting information on potential mental health/psychosocial problems from families in primary care or other types of pediatric and adolescent clinical settings. These questionnaires explore issues that parents and teens may be thinking about or reveal areas of concern. The chapter also presents screening tools that can be provided to children and adolescents.