Since the formulation of the hopelessness theory of depression (Abramson, Metalsky, & Alloy, 1989) a quarter century ago, it has garnered considerable interest. The current paper presents a systematic review of this theory including its subsequent elaborations (Rose and Abramson’s [1992] developmental elaboration, Abela and Sarin’s [2002] weakest-link approach, Panzarella, Alloy, and Whitehouse’s [2006] expansion of the hopelessness theory, and the hopelessness theory of suicide [Abramson et al., 2000]), followed by recommendations for future study. Although empirical support was consistently found for several major components of the hopelessness theory, further work is required assessing this theory in relation to clinically significant phenomena. Among the most significant hindrances to advancement in this area is the frequent conceptual confusion between the hopelessness theory and the reformulated learned helplessness theory.