He was born in 1902, graduated from Oakland Technical High School in 1919, and studied at the University of California, Berkeley (B.A. and M.A.) and at the Sorbonne (Ph.D.). A student of the linguist Antoine Meillet at the Sorbonne, Parry revolutionized Homeric studies. In his dissertations, which were published in French in 1928, he demonstrated that the Homeric style is characterized by the extensive use of fixed expressions, or 'formulas', adapted for expressing a given idea under the same metrical conditions. Meillet introduced him to Matija Murko, who had worked on oral epic traditions in Bosnia and had made phonograph recordings of some performances.
Between 1933 and 1935 Parry, at the time Associate Professor at Harvard University, made two trips to Yugoslavia, where he studied and recorded oral traditional poetry in Serbo-Croat with the help of his assistant Albert Lord and Nikola Vujnović, a local Herzegovinian Croat. They worked in Bosnia where literacy was lowest and the oral tradition was, in the term used by Parry and Lord, "purest". The two are now famous for their work in orality/literacy, which has come to be known as the Parry/Lord thesis.
In his American publications of the 1930s Parry introduced the hypothesis (first suggested to him by Meillet and amply demonstrated in his own fieldwork) that the formulaic structure of Homeric epic is to be explained as a characteristic feature of oral composition (the so-called Oral Formulaic Hypothesis). It was continued by Albert Lord, most notably in The Singer of Tales (1960). Though the book does not present his argument specifically, the assumed thesis is supported through in-depth content analysis of various singers (performers of the oral tradition or composition process) and interviews of the same singers. Parry moves against structural traditions declaring the original text is the purest form of the text (à la Walter Benjamin); rather, Parry asks us to understand that "the truth of the matter is that our concept of 'the original,' of 'the song,' simply makes no sense in oral tradition" (Lord, 2000, p. 101).
He died in Los Angeles from an accidental gunshot while unpacking his suitcase. This claim, however, has never been proven and is disputed. Parry was denied tenure at Harvard leaving many believing he had taken his own life. 
Parry's collected papers were published posthumously: The Making of Homeric Verse: The Collected Papers of Milman Parry, edited by Adam Parry, his son (Oxford University Press, 1971). The Milman Parry collection of records and transcriptions of South Slavic heroic poetry is now in the Widener Library of Harvard University.
Parry's influence is evident in the work of later scholars who have argued that there is a fundamental break in the institutional structure between Homeric Greece and Platonic Greece, a break characterized by the transition from an oral culture to a written culture. This line of thought holds that oral poetry, in Homeric society, served as a sort of log of institutional and cultural practices. In a written culture, written logs take the place of oral poetry. This thesis is associated with Eric Havelock, who cites Parry. Havelock argues that the fixed expressions Parry identifies can be understood as mnemonic aids used to help the poet remember the poetry, which was indeed vital to the well-being of the society, given the importance of the information carried by the poetry. It can be argued however that the epithets do contribute to the overall meaning of the epic. For example "swift footed Achilles" can be seen as looking forward to Hector and Achilles' race around the walls of Troy.
- "Milman Parry, Class of 1919". School Historical Archive. Retrieved 1 March 2016.
- A. Parry, Making of Homeric Verse xli.
- (No writer attributed.) (December 4, 1935). "PARRY, GREEK AND LATIN PROFESSOR, KILLED YESTERDAY". The Harvard Crimson. Retrieved 25 April 2015.
Hanson, V. J. and Heath, John. 1998. Who Killed Homer? (New York). The Free Press.