Fred Casmir's third culture building (TCB) framework made a major theoretical contribution to communication studies. Casmir conceptualized the framework as an active process whereby different cultural groups come together to form a third culture between them. The third culture then becomes a common ground for all participants; a cognitive space that incorporates elements of both cultures and yet remains separate and distinct. Third culture building is a departure from adoption (the process of taking on the cultural mores of another) or adaptation (modifying one's cultural mores to better fit those of another), and achieved through deliberate development in an extended process, during which all participants gain an understanding of, and appreciation for, one another. In this essay, the authors review the life and work of Fred Casmir – a leading figure in establishing intercultural communication as a specific area of study. Next the authors discuss the ideological foundations, intended use, key applications and heuristic value of Casmir's third culture building framework.