When people ruminate about an unfortunate encounter with a loved one, savor a long-sought accomplishment, or hold in mind feelings from a marvelous or regretfully tragic moment, what mental processes orchestrate these psychological phenomena? Such experiences typify how affect interacts with working memory, which we posit can occur in three primary ways: emotional experiences can modulate working memory, working memory can modulate emotional experiences, and feelings can be the mental representations maintained by working memory. We propose that this last mode constitutes distinct neuropsychological processes that support the integration of particular cognitive and affective processes: affective working memory. Accumulating behavioral and neural evidence suggests that affective working memory processes maintain feelings and are partially separable from their cognitive working memory counterparts. Affective working memory may be important for elucidating the contribution of affect to decision making, preserved emotional processes in later life, and mechanisms of psychological dysfunction in clinical disorders. We review basic behavioral, neuroscience, and clinical research that provides evidence for affective working memory; consider its theoretical implications; and evaluate its functional role within the psychological architecture. In sum, the perspective we advocate is that affective working memory is a fundamental mechanism of mind.