Corticotropin-releasing factor (CRF) is a chemical found naturally in the brain that plays a key role in the stress response. CRF is also known to be involved in anxiety and mood disorders, as well as various aspects of drug dependence, including long-term relapse to drug use. Pathological symptoms in the form of mood disorders and substance abuse occur, at least in part, as a result of aberrant activity within CRF systems. From this perspective, CRF is a logical target for drug development in the treatment of these disorders.