This paper presents a coherent account of affect based on the functional properties of the nervous system. The paper begins with a brief discussion of the nature of a structural theory and contrasts it with a functional view. Then the functional view is discussed in more detail. The following two assumptions of the functional view are described: emotions are created by the simultaneous activity of various components of the neuronal system and emotional structures persist only as long as the underlying neuronal elements remain in a state of functioning. Next, the paper demonstrates that traditional psychological research on affective variables is more consistent with a functional theory of affect as opposed to a structural theory. Finally, some of the empirical implications of the functional view are discussed in terms of the study of affective functioning. (RL)