Abstract: A defining characteristic of addiction is the gradual shift in preference from natural rewards, such as food, to drugs of abuse. Rodent models of addiction have established that females have a higher propensity for addiction and choose cocaine over food more often and more rapidly than males do. We hypothesize that the sex differences observed in drug seeking are due, in part, to differences in the underlying neurobiology of the reward circuitry between the sexes. Utilizing rodents in a choice self-administration behavioral paradigm eventually some rats develop a preference for cocaine over a palatable food reward over the course of seven weeks. Using in vivo microdialysis in the dorsal striatum and contralateral nucleus accumbens, this set of experiments repeatedly characterized cocaine-induced dopamine increases during self-administration in the choice paradigm.