A necessary first step in the psychosocial treatment of persons with severe mental illness is helping them identify their goals. Unfortunately, goal assessment is often viewed as a categorical process in which individuals list needs for which they require services. Motivational interviews provide a more sophisticated approach in which persons specify the costs and benefits to each of the needs in the list. Benefits define the reasons why a person should pursue a goal; costs define barriers to achieving that goal. The basic mechanisms for understanding and implementing motivational interviews are summarized. Ways to circumvent barriers to motivational interviews are also discussed.