Anxiety Disorder Association of America (ADAA)
The mission of the Anxiety Disorders Association of America (ADAA) is to promote the prevention, treatment, and cure of anxiety and stress-related disorders through advocacy, education, training, and research.  ADAA offers useful information for the treatment of anxiety disorders, resources for support, and tips for helping friends and relatives.
Association of Behavioral & Cognitive Therapies (ABCT)
The Association for Behavioral and Cognitive Therapies is an interdisciplinary organization committed to the advancement of a scientific approach to the understanding and amelioration of problems of the human condition. These aims are achieved through the investigation and application of behavioral, cognitive, and other evidence-based principles to assessment, prevention, and treatment. 
Obsessive-Compulsive Foundation (OCF)
The goals of the OCF are to raise awareness and improve the quality of treatment provided for OCD; support research into the cause of, and effective treatments for; OCD and related disorders; to improve access to resources for those with OCD and their families; and advocate and lobby for the OCD community.

National Institute of Mental Health (NIMH)
The mission of NIMH is to transform the understanding and treatment of mental illnesses through basic and clinical research, paving the way for prevention, recovery, and cure.  NIMH envisions a world in which mental illnesses are prevented and cured.