How does mood influence employee creativity? We address this question through a daily longitudinal field study of 222 employees in 7 companies in 3 industries. Although research on this question has previously been confined primarily to the psychological laboratory, this study uses daily real-time measures to track the relationship between the mood and creativity of employees as they work on creative projects. We find that positive mood predicts employee creative thinking, self-rated creativity, and peer-rated creativity. Moreover, lagged analyses suggest that positive mood leads to creativity; there was only weak evidence that creativity leads to positive mood. Although enduring positive dispositional affect independently predicts peer-rated creativity, the basic mood-creativity relationship holds even controlling for dispositional affect. These results have implications for theories of affective processes in organizational creativity and cognition, and practical ramifications for the management of creativity.