The Fundação Mário Soares (Mario Soares Foundation, Portugal) is a non-profit private foundation, which is named after the former President of Portugal, Mario Soares. The foundation's Arquivo & Biblioteca Online offers access to the Diário de Lisboa (Lisbon Daily) from April 1921 to November 1990 and a collection of archival materials about various subjects and individuals:

• Abel Salazar.
• Afonso Costa.
• Bernardino Machado.
• CMIO/Ocean Governance XXI.
• Fotografias Mário Soares (photographs of Mário Soares).
• Fotografias Portugal Político (photographs of Portugese politic events).
• Instituto de Ciências Sociais (Institute of social science).
• Manuel Teixeira Gomes.
• Mário Pinto de Andrade.
• Periódicos (Periodical: Diário de Lisboa only).
• Resistência Timor-Leste (1973-2005) (East Timor Resistance).
• Revistas de Ideias e Cultura (Journal of Ideas and Culture).