Much has been learned about mood and temperament in recent years--yet until now, investigations into these domains have remained relatively distinct and disconnected. This groundbreaking volume presents a comprehensive framework for understanding short-term mood fluctuations and their relationship to longer-term differences in temperament and emotionality. David Watson integrates key findings from both literatures within the context of his own ongoing 20-year research program on daily mood. Illuminated are the basic properties of everyday moods, the processes that produce change, and the connections between affective experience, personality, health, and psychopathology. Providing a clear summary and synthesis of a vast body of knowledge, this unique book will be of interest to readers across a wide range of psychological disciplines.