For nearly twenty years, John Buchan was a regular contributor to the American pulp magazines Adventure, All-Story, Argosy and Street & Smith's Popular Magazine. These all-fiction, pulp-paper magazines – or ‘pulps’ as they became known – were the major source of literary entertainment for most Americans during the first half of the twentieth century. They were printed on rough, low-quality paper, distributed in record numbers and sold by the millions on newsstands across the US and Canada. Between 1910 and 1928 they were also the medium towards which Buchan consistently directed most of his new fiction for the North American market. With the extended circulations granted to some of these stories through 1930s and 1940s reprints, Buchan's literary relationship with pulp magazines would last for nearly half a century. This chapter suggests that a more significant, and more symbiotic relationship existed between Buchan and the American pulp magazines than has ever been acknowledged. The periodical contexts that surrounded Buchan's pulp publications, moreover, characterize the author's close association with this medium as one of mutual literary influence. In the transatlantic context of his first North American serializations of popular spy fiction in pulp magazines, Buchan is shown to be an expert navigator of modern media environments and highly-skilled manager of literary returns and reputations.