John Cacioppo, a pioneer of social neuroscience at the University of Chicago, sits down with Yale's June Gruber for this entry in the Experts in Emotion series. Cacioppo traces how he came to study psychophysiology, the use of measures like facial electromyography and cardiovascular response to track emotional and social processes in the body. He walks through the central findings of his career, including his work on loneliness and its physiological costs, and how attitudes and social behavior show up in measurable bodily signals. The interview moves into what he sees as the open frontiers in the field, from new technology for measuring physiological response to unresolved questions about how emotion and cognition interact. It closes with his advice for students weighing a career in emotion research. The format is a seated conversation rather than a classroom lecture, but the content is substantive and specific to Cacioppo's own research program.