This is a history of Eighteenth-Century Collections Online, a database of over 180,000 titles. Published by Gale in 2003 it has had an enormous impact of the study of the eighteenth century. Like many commercial digital archives, ECCO's continuing development obscures its precedents. This Element examines its prehistory as, first, a computer catalogue of eighteenth-century print, and then as a commercial microfilm collection, before moving to the digitisation and development of the interfaces to ECCO, as well as Gale's various partnerships and licensing deals. An essential aspect of this Element is how it explores the socio-cultural and technological debates around the access to old books from the 1930s to the present day: Stephen Gregg demonstrates how these contexts powerfully shape the way ECCO works to this day. The Element's aim is to make us better users and better readers of digital archives. This title is available as Open Access on Cambridge Core.