In 1964, Kohl's first book, "The Age of Complexity", about analytic and existential philosophy, was published at the same time that he was teaching sixth grade. His first writings on education, "Teaching the Unteachable" (New York Review of Books, New York, 1967) and "The Language and Education of the Deaf" (The Urban Review Press, New York, 1967), set the themes for much of his future work. They centered on advocating for the education of poor and disabled students and critiquing and demystifying the stigmatization of students who are perfectly capable of learning.