A new understanding of substance abuse explores treatment issues based on subtypes of addicts, with a special focus on antisocial personality disorder and functional addiction.• Case studies of real people that illustrate the three subtypes of addicts• Offers specific intervention and treatment recommendations based on subtype• Gives a firsthand look at actual functional addicts who continue to use illicit drugs• Presents a realistic discussion of the poor prognosis for antisocial personality addicts and what can be done to manage this population