Stress is an important factor known to increase alcohol and drug relapse risk. This paper examines the stress-related processes that influence addiction relapse. First, individual patient vignettes of stress- and cue-related situations that increase drug seeking and relapse susceptibility are presented. Next, empirical findings from human laboratory and brain-imaging studies that are consistent with clinical observations and support the specific role of stress processes in the drug-craving state are reviewed. Recent findings on differences in stress responsivity in addicted versus matched community social drinkers are reviewed to demonstrate alterations in stress pathways that could explain the significant contribution of stress-related mechanisms on craving and relapse susceptibility. Finally, significant implications of these findings for clinical practice are discussed, with a specific focus on the development of novel interventions that target stress processes and drug craving to improve addiction relapse outcomes.