The studies reported here address two related issues: how the various medial-frontal/anterior cingulate processes observed in electrophysiological and neuroimaging studies are related, and what the functional roles of these processes are in monitoring and regulating behavior. A variety of medial-frontal negativities are evident in diverse experimental paradigms (e.g., the ERN/Ne, the negativities elicited by error feedback and monetary losses, and the various N2s). One experiment employed time-frequency analysis (using continuous wavelet transforms) to determine whether these negativities arise from the same underlying pattern of brain activity. The response-locked ERN and the ERN-like activity elicited by monetary losses were each apparent as a burst of activity in the 4-7 Hz (theta) range. Variations in the scalp distribution of this theta activity suggest that the two phenomena are not identical, although there may be sources common to both. A second study explored the numerous ways in which a feedback stimulus can be "good or bad" and "expected or unexpected.” Here, we examined the feedback-related negativities elicited by feedback stimuli signifying the rewards that were missed or penalties that were avoided because of a prior choice made by the subject. We observed several conditions in which feedback representing a favorable outcome elicited a feedback-related negativity as large as that elicited when the outcome was bad. Our results suggest that theories of medial-frontal function must accommodate the multiple neural sources of the scalp activity and the multiple ways in which a stimulus can deviate from contextually-determined expectancies.