<p>This article deals with the early development of preprint communication in high-energy physics (HEP), specifically with how preprint communication was formalized in the early 1960s at the European Organization for Nuclear Research (CERN). It employs a sociological conception of infrastructures to ask which practices and technologies of communication structured the use of preprints in HEP at the time and subsequently solidified into the research community’s communication and information system. The text conducts an archaeology of the early preprint infrastructure along three systematic-historical explorations: 1) the use of preprints as media to privately and informally share practical instructions and theoretical tools in the fast-moving current of postwar physics; 2) the institutional and organizational context of library and documentation at CERN around mid-century, which acted as a backdrop for creating the preprint infrastructure; and 3) the actual formalization of preprint communication into an information system at the CERN library in the early 1960s, which treated preprints as public “current awareness tools” for the benefit of the whole HEP community, informing members of recent progress in the field. The article concludes with a discussion of what we can learn from the pre-Web history of preprint communication in HEP about current understandings of scientific communication.</p>