Mental illnesses are common in the United States. It is estimated that more than one in five U.S. adults live with a mental illness (57.8 million in 2021). Mental illnesses include many different conditions that vary in degree of severity, ranging from mild to moderate to severe. Two broad categories can be used to describe these conditions: Any Mental Illness (AMI) and Serious Mental Illness (SMI). AMI encompasses all recognized mental illnesses. SMI is a smaller and more severe subset of AMI.

In 2021, there were an estimated 57.8 million adults aged 18 or older in the United States with AMI. This number represented 22.8% of all U.S. adults.

The prevalence of AMI was higher among females (27.2%) than males (18.1%).

Young adults aged 18-25 years had the highest prevalence of AMI (33.7%) compared to adults aged 26-49 years (28.1%) and aged 50 and older (15.0%).

The prevalence of AMI was highest among the adults reporting two or more races (34.9%), followed by American Indian / Alaskan Native (AI/AN) adults (26.6%). The prevalence of AMI was lowest among Asian adults (16.4%).