The processes that underlie the transition from controlled to uncontrolled consumption of ethanol are unknown. Behavioral sensitization is proposed as one of these processes and occurs with repeated administration of psychomotor stimulants whereby both behavioral and neurochemical responses to the drugs are progressively enhanced. Because ethanol shares some actions in common with these drugs, chronic exposure to ethanol may intensify its reinforcing properties. The effect of ethanol on several behavioral models suggests that behavioral sensitization may develop especially in the presence of environmental cues. Thus, a research opportunity exists to study factors that contribute to an increasing probability of progressively higher ethanol consumption. Knowledge of these factors will lead to a better understanding of why some people drink uncontrollably.