In this chapter, we outline the progression of research on facial actions associated with emotion within the discipline of psychology. We outline two dominant perspectives, one emphasizing emotions as natural kinds, and the other emphasizing emotions as constructed events. We provide an overview of the critical assumptions of each theoretical approach and demonstrate the recurring themes and tensions in the repeated emergence of these two perspectives over time. We close by suggesting that the science of emotion is, yet again, at a critical precipice with the emergence of computationally powerful computer-vision approaches and that careful consideration of the lineage of these two theoretical perspectives will allow for progress to be made with these approaches.