The use of alcohol and other legal as well as illegal chemical substances is a growing problem in many societies. Substance abuse has a profound effect on the mortality and morbidity of many patients, their families, and their communities. The social cost related to accidental death, violence, loss of productivity in the workforce, and unemployment can only be estimated. This chapter serves as a general overview of substance abuse problems and challenges for the provider. Patient-centered care would rely on assessing and intervening into patterns of substance use as soon as possible. Primary care providers must first examine their own attitudes about substance abuse. Providers are encouraged to incorporate principles of drug addiction treatment into their daily interaction with patients. The effect of substance abuse on body systems ranges from temporary impairment to multisystem failure. Children whose parents were alcohol or drug abusers may be influenced to use as well.