There is increasing evidence for adolescence as a time period vulnerable to environmental perturbations such as stress. What is unclear is the persistent nature of the effects of stress and how specific these effects are to the type of stressor. In this review, we describe the effects of chronic, unpredictable stress (CUS) exposure during adolescence on adult behavior and brain morphology and function in animal models. We provide evidence for adolescence as a critical window for the effects of physical GUS that persist into adulthood, with ramifications for morphological development, associated hippocampal-dependent tasks, and anxiety- and depressive-like behaviors. The results of this investigation are contrasted against those of social GUS stress exposure from the same time period that show reversible and, in the case of responses to drugs of abuse, potentially protective effects in adulthood. Finally, we discuss potential underlying mechanisms for these morphological and behavioral findings. It is our aim that the research highlighted in this review will aid in our understanding of the role of stress in adolescent mental health and development. This article is part of a Special Issue entitled: Stress, Emotional Behavior and the Endocannabinoid System. This article is part of a Special Issue entitled: Stress and the Adolescent Brain. (C) 2012 Published by Elsevier Ltd. on behalf of IBRO.