Disorders are diagnosable conditions characterized by changes in thinking, mood, or behavior (or some combination of these) that can cause a person to feel stressed out and impair his or her ability to function. These disorders are common in adolescence. This Adolescent Health Highlight presents the warning signs of mental disorders describes the types of mental disorders and their prevalence and trends discusses the consequences and risk of mental disorders presents treatment options and barriers to accessing mental health care and provides mental health resources.