Corticotropin-releasing factor (CRF) is the major peptide involved in regulating the body’s autonomic, hormonal, and behavioral responses to stress. Cells that produce and release this peptide are widely distributed throughout the brain. This dissertation focuses on a specific population of CRF cells residing in the medial prefrontal cortex (mPFC) that could potentially influence a number of higher order functions through modulation of local circuits. The prefrontal cortex is known to function sub-optimally in patients suffering from various stress-related psychiatric conditions including alcohol use disorder (AUD), and dysregulated CRF signaling may be an underlying mechanism. Surprisingly little is known about this population of cells. A primary objective of this dissertation was to characterize these cells and determine how they fit anatomically and functionally into the local circuitry of the mPFC. I show that although mPFC CRF cells are inhibitory interneurons, a relatively small number of CRF puncta co-expressed the rate-limiting enzyme for GABA production indicating that CRF and GABA may be independently released. Co-expression patterns differed in the dorsal versus ventral mPFC indicating anatomical diversity in the modulation of pyramidal circuits by CRF. These subtle differences in CRF micro-circuitry may facilitate a highly complex biological response to stress. I also examined possible links between AUD vulnerability and mPFC CRF using two models associated with increased drinking: predator odor stress and adolescent binge drinking. Predator odor stress increased CRF cell density, but adolescent binge drinking decreased CRF labeling intensity in the ventral portion of the mPFC. Thus, while high mPFC CRF may promote heavy drinking, alcohol-induced increase in peptide production does not appear to be the mechanism by which adolescent alcohol increases vulnerability to AUD. No sex differences were observed in several measurements of the CRF system in the mPFC of adolescent rats. Altogether my results suggest that CRF cells differentially modulate the dorsal and ventral mPFC and may play a complex role in alcohol drinking. These findings provide groundwork for understanding this peptidergic system and should help direct future investigation aimed at elucidating the details of CRF-mediated cellular and molecular mechanisms underlying functions regulated by the mPFC.