Satisfactory models of the nature and treatment of excessive gambling must incorporate behavioural, cognitive, emotional and physiological findings. The acquisition of gambling behaviour is apparently influenced by social exposure and financial reinforcement. Continuation is promoted by partial reinforcement schedules and biased cognitions. Excessive gambling also involves changes in the individual's internal state, including physiological arousal, euphoria, distraction and perceived control. These effects might depend on the prior characteristics of the individual. Treatment should remove conditioned triggers, establish alternative means of financial and internal regulation, and reduce the individual's need for the financial and subjective rewards provided by gambling. Treatment goals and resources are discussed.