He first came to notice with an influential review of Noam Chomsky's Syntactic Structures (1957) and with his 1960 book The Grammar of English Nominalizations.
He then enrolled in the electrical engineering department at MIT, from which he obtained his Ph.D. in linguistics under Chomsky.
Lees' role in fostering Chomskian transformational generative grammar is discussed in Newmeyer (1986: 35-36).
He taught intensive courses on contemporary linguistics at Delhi University and at the Central Institute of English and Foreign Languages in Hyderabad.
A famous example is his response when informed that Nelson Francis had received a grant to produce the Brown Corpus: "That is a complete waste of your time and the government's money.