Many social scientists have used the logic behind the theory of natural selection (TNS) to advance more specific theories about how natural selection shapes human psychology and behavior. This chapter describes the intellectual tradition and main goals and features of TNS. It comments on how TNS conceptualizes communication and illustrates some of the many ways it can inform research on family communication. It evaluates the theory's merits and suggesting future directions for research. TNS is a scientific theory that most closely aligns with the paradigmatic assumptions of what is now called the post-positivist tradition. Its focus on explanation and prediction, that is, reflect a post-positivistic epistemology. TNS is applicable to family behavior via evolutionary psychology (EP), the application of natural selection to the evolution of social, mental, and psychological characteristics. The evolutionary approach to human behavior is exceedingly broad in the range of family relationships and behaviors it can explain.