This chapter provides a brief introduction to the field of physiological economics. We begin by articulating why physiology is important for understanding the behavior of economic agents. Focusing primarily on hormonal signals, we outline basic concepts in endocrinology. We provide a description of the most commonly analyzed hormones, including their biological relevance and how they are measured. We then proceed to describe the available evidence pertaining to the relation between hormones and economic behavior, including both individual and social decision-making. We end by briefly exploring limitations, challenges, and potential future directions.