Two theoretical perspectives—functionalism and constructionism—predominate modern research on emotion. This introductory chapter describes these perspectives and offers points of convergence and divergence. It pays special attention to common misconceptions about functionalism and to strengths and limitations of each perspective. Functionalism, which draws in part from phylogenetic accounts of emotion and motivation, is limited by difficulties drawing inferences about human emotion from animal research, even though animal research is conducted using very precise methods of high spatial and temporal resolution. In contrast, constructionism is limited by difficulties falsifying its core propositions given reliance on research using functional magnetic resonance imaging, which has poor temporal resolution. These limitations notwithstanding, both functionalism and constructionism have much to offer current interpretations of and future research on emotion dysregulation. Thus, pitting the perspectives against one other is counterproductive.