This paper explores the intriguing and hitherto neglected question of contact between Edward Sapir (1884–1939) and members of the Prague Linguistic Circle (1926–1939) concerning the development of phonemic theory. The point of departure is Cain’s (1980) conjecture that the Prague Anglicists (Mathesius, Trnka, and Vachek) were more likely to have encountered the writings of Sapir than Sapir was to have read Jakobson’s and Trubetzkoy’s Czech and Russian publications. Sapir’s published theoretical works provide no evidence of contact with or knowledge of classical Prague School phonology. However, a thorough study of the relevant Prague School publications reveals that three of Sapir’s theoretical writings and three of his language monographs were well known to some of its members. Interestingly, three of the seven references to Sapir by the Anglicists appear in their German and Czech writings, while the largest number of references to Sapir occur in Trubetzkoy’s published scholarly works and letters written primarily in German and Russian. Trubetzkoy’s letters provide valuable supplementary evidence of personal communication between him and Sapir. Collation of material in the letters with passages in Trubetzkoy’s publications reveals that Sapir and members of the Prague School (Jakob-son, Mathesius, Trubetzkoy) were in personal contact from 1929, three years after the founding of the Circle. It also emerges that Trubetzkoy had read Sapir (1925) in a copy of the journal Language which Mathesius had lent to him as early as 1928, while Sapir had read vol. 1 of the Travaux and commented favorably on it to Trubetzkoy in 1929. Although Sapir and the Prague School developed their views on phonemic theory independently, Trubetzkoy’s articles and letters occasionally reveal fairly technical discussion of theoretical points and problems in the phonological systems of specific languages raised by Sapir. Finally, the letters provide convincing evidence that Trubetzkoy and Sapir shared an ongoing professional concern with advancing the cause of phonology in the international linguistic community. Sapir and members of the Prague School expended considerable effort toward a favorable reception of phonology by the American linguists (e.g., Leonard Bloomfield, Boas, Kent, Kurath, and Twaddell). In this connection, Sapir was very actively involved in the American branch of the Internationale phonologische Arbeitsgemeinschaft from its inception in 1932 during the Second International Congress of Phonetic Sciences in Amsterdam. Although Sapir and Trubetzkoy appear never to have met in person, the IP A turned out to serve as a pivotal link between Sapir and Trubetzkoy and, by extension, between the Linguistic Society of America and the Prague Linguistic Circle.