The present chapter presents an approach to studying emotion in education and achievement settings through the noninvasive assessment of autonomic nervous system (ANS) activity. Part one outlines structure and function of the ANS, introduces three principles central to the conceptualization of ANS activity—bidirectionalism, allodynamic control, and bivariate autonomic space—and identifies the autonomic index function of cardiovascular, electrodermal, and respiratory measures. Part two illustrates application of the three principles of ANS activity in experimental paradigms relevant to the study of emotion in education and achievement settings. We highlight bidirectional ANS–brain effects in the context of test anxiety; allodynamic control of effort investment in cognitive task performance; and assessment of autonomic effects of achievement emotion according to the conceptualizatin of bivariate autonomic space. Part three outlines avenues for future research on emotion in education and achievement settings afforded by the application of the three principles of ANS activity.