The goal of this chapter is not to rephrase excitation-transfer theory and three-factor theory. Their creator has dutifully updated and refined these theories whenever fresh empirical evidence or emerging conceptual developments warranted. References to these updates are provided throughout this chapter, and it should be noted that Zillmann has continued this tradition in the final chapter of this volume. Space does not allow us to attempt a history of the programmatic development of this theory or the innovative designs and methodologies used to develop them. Rather, what we have attempted to do is showcase the fine threading and lacing of theory construction that produced excitation-transfer theory and then molded it into the three-factor theory of emotion.