He remained at Buffalo until 1980 when he retired from the university and moved to New York City, where he worked as a private consultant and pursued independent research in cultural evolution and the arts, especially the ballet.
He was on the Editorial Board of the Journal of Social and Evolutionary Systems and starting in 1989 was a member of Connected Education's online faculty for their MA in Media Studies offered through The New School.
During his years at RAND he worked on the machine translation of Russian technical literature into English and more generally on computational linguistics, a term that he created.
More than anyone else Hays is responsible for the realization that language processing should consist in the application of theoretically motivated grammars to specific texts by general algorithms.
After leaving RAND and assuming his position at Buffalo, Hays turned to more a more general interest in language and cognition and, ultimately, the evolution of human culture.