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Initially, the books were mostly in English. As the original Project Gutenberg is based in the United States, its first focus was the English-speaking community in the country and worldwide. In October 1997, Michael Hart expressed his intention to digitize ebooks in other languages. In early 1998, the catalog had a few titles in French (10 titles), German, Italian, Spanish and Latin. In July 1999, Michael wrote: "I am publishing in one new language per month right now, and will continue as long as possible."
In the 2000s, multilingualism became a priority for Project Gutenberg, like internationalization, with Project Gutenberg Australia (created in August 2001), Project Gutenberg Europe (created in January 2004), Project Gutenberg Canada (created in July 2007), and others to come.
The launching of Project Gutenberg Europe and Distributed Proofreaders Europe (DP Europe) by Project Rastko was an important step. Founded in 1997, Project Rastko is a non-governmental cultural and educational project. One of its goals is the online publishing of Serbian culture. It is part of the Balkans Cultural Network Initiative, a regional cultural network for the Balkan peninsula in south-eastern Europe.