Each year since 1991, Screening for Mental Health Inc., a nonprofit agency based in Massachusetts, has organized NDSD. The event, which is held at nearly 6,000 screening sites throughout the United States and Canada, aims to help those with mood and anxiety disorders find treatment, educate the public about those disorders, and combat the stigma of mental illness. Last year about 100,000 people received screening for mood disorders. A similar number of people are expected to attend screenings this year.