This paper addresses the mechanisms underlying the effects of emotions on voice and speech, with a particular emphasis on intonation contours. After reviewing a number of conceptual issues, such as the different types of affective states, the nature of vocal affect communication, and the effects of push and pull factors on intonation, we describe an empirical study that examines statistically the existence of emotion-specific intonation contours by using a new coding system for the assessment of F0 contours in emotion portrayals. Throughout this paper, some suggestions for future work in this area are introduced.