This document summarizes the history and impact of mobile libraries in Portugal over the past 50 years. It notes that the first Portuguese mobile library began in 1953 and that the Calouste Gulbenkian Foundation operated 62 mobile libraries between 1958-2002 that loaned over 97 million books to 29 million readers across Portugal. The mobile libraries provided library services to rural communities, visiting on a periodic basis to deliver books, reference services, and literary programs and establishing a sense of proximity, periodicity, and friendship with patrons.