Individuals are considered mentally ill chemical abusers (MICAs) when they exhibit psychotic behaviors and are actively abusing alcohol and/or drugs; are actively psychotic with a history of alcohol or drug abuse; and/or are actively abusing alcohol or other drugs and have a history of severe psychiatric diagnoses. Although some practitioners use different diagnostic labels, MICAs present a clear constellation of behaviors, symptoms, and risk factors, and require specific treatment technologies. Mental health and chemical dependency practitioners noted a rise in the number of MICA clients during the last ten years due to a number of contributing factors, such as the exodus of persons from state hospitals to community care. In the past, treatment for these individuals was hampered by conflicting or uncoordinated treatment programs, misdiagnosis, damaging myths about MICAs, and failure to distinguish between psychiatric disability and chemical dependency. Today, a treatment protocol for the MICA client is emerging and practitioners now agree on a number of treatment strategies: (1) both illnesses must be treated concomitantly; (2) the illness given priority is the one most florid at the time of admission; (3) the psychiatric illness must be controlled to deal with the active chemical dependency; and (4) chemical dependency must be stabilized to treat the psychiatric illness. (RJM)