People want their partners to be responsive to their needs and wishes, and when they perceive that their partners have been responsive, individuals and their relationships typically thrive. Yet relationship scientists has yet to agree on a comprehensive theory of what responsiveness is and how it influences the development and maintenance of relationships. In this address, I will describe our efforts to forge a general theory of responsiveness, illustrating that theory with diverse empirical evidence. The theory emphasizes both behavior and perception, and provides insights for understanding how modern technology has the potential to help and hinder close relationships.