Two experiments are proposed to test some of the core hypotheses of the incentive-sensitization theory of drug addiction. This theory provides a basic framework for understanding drug abuse and thus may eventually lead to more effective treatments for addiction. A critical, emperical evaluation of the theory's validity is therefore essential. In the first experiment, the impact of intra-accumbens d-amphetamine on measures of incentive salience is predicted to be sensitized in drug pre-treated animals. In the second experiment, the presentation of drug-paired stimuli is predicted to enhance measures of incentive salience without altering measures of hedonics. Both of these experiments will lead to a better understanding of the role of dopaminergic circuitry in regulating incentive motivation and addiction.