Although contradicting evidence exists, the production of new neurons, or neurogenesis, has convincingly been shown in countless mammalian species up into adulthood, namely in the subventricular zone and hippocampal dentate gyrus. Stress has been shown to alter brain plasticity, and furthermore, inhibit neurogenesis in the hippocampus in which changes appear to be mediated not only by glucocorticoid hormones and their interaction with gonadal hormones, but also by the context in which stress occurs, and the valence and duration of the stressor. This chapter provides an overview of the role of stress in adult hippocampal neurogenesis and how these stress-induced changes may alter or change behavior and cognition, suggesting a potential target for better understanding stress-related disorders.