We argue that creativity is influenced by the dynamic interplay of positive and negative affect: High creativity results if a person experiences an episode of negative affect that is followed by a decrease in negative affect and an increase in positive affect, a process referred to as an "affective shift." An experience-sampling study with 102 full-time employees provided support for the hypotheses. An experimental study with 80 students underlined the proposed causal effect of an affective shift on creativity. We discuss practical implications for facilitating creativity in organizations.