IMDs are facilities with 16 or more beds where people get diagnosis, treatment, and care (including medical and nursing care) for a mental health disability.^[1]42 CFR Section 435.1010 In California, IMDs can be psychiatric hospitals, psychiatric health facilities (PHF), skilled nursing facilities with special treatment programs (SNF-STP), mental health rehabilitation centers (MHRC), or state hospitals.

For people with developmental disabilities, IMDs are very restrictive settings.