This chapter considers the role of correspondence in the establishment and maintenance of the international concrete poetry movement, and in the transmission and negotiation of concrete poetics. The chapter draws upon social network analysis (SNA), focusing on the ‘ego network’ constructed by Morgan and his correspondents. By analysing the range of fellow poets, editors, artists, curators, readers and arts administrators who feature in the published and unpublished archives of Morgan’s correspondence, scholars can identify those who were central and marginal to Morgan’s ‘concrete network.’ A qualitative survey of the contents of letters by Morgan and others reveals how the ethos and poetics of concrete poetry were dynamically negotiated through correspondence.