Onésimo Teotónio Almeida was born in S. Miguel, Azores, in 1946. A graduate from the Portuguese Catholic University, Lisbon, in 1972, he received his M.A. (1977) and Ph.D. (1980) in Philosophy from Brown University. In 1975. Professor in the Department of Portuguese and Brazilian Studies, where he was Chair between 1992 and 2003, he also teaches a University Course on Values and Worldviews for the Wayland Collegium.
Author and editor of numerous books, his most recent are O Século dos Prodígios. A Ciência no Portugal da Expansão (Quetzal, 2018) (Gulbenkian Prize, Academia Portuguesa de História, 2018, and D. Diniz Prize, Casa de Mateus, 2019); A Obsessão da Portugalidade (Quetzal, 2017); Despenteando Parágrafos: Polémicas suaves (Quetzal, 2015); Pessoa, Portugal e o Futuro (Gradiva, 2014); Minima Azorica: O Meu Mundo É Deste Reino (Companhia das Ilhas, 2014); O Peso do Hífen, Ensaios sobre a experiência luso-americana (Imprensa de Ciências Sociais, 2010); De Marx a Darwin: A desconfiança das ideologias (Gradiva, 2009; Prize Seeds of Science for the Social Sciences and Humanities, Ciência Hoje, 2010). A booklength interview with him on his works was published by João M. Brás under the title Utopias em Dói Menor. Conversas transatlânticas com Onésimo (Gradiva, 2012).
He is the author of more than two hundred essays published in various collective volumes and academic journals. The founder and editor of Gávea-Brown, a journal specializing in the recording of the Portuguese experience in North America, he is also co-editor of the e-Journal of Portuguese History, as well as of Pessoa Plural, a journal on the works and life of Fernando Pessoa. He is co-editor of a book series on Lusophone themes published by Sussex Academic Press, in the United Kingdom.
He was a member of the Board of the Rhode Island Committee for the Humanities from 1995 to 2001, and its Vice-President from 1998 to 2000. The recipient of various awards, The President of Portugal honored him in 2019 with the Grã-Cruz of the Prince Henry Order. He was elected to the Academia da Marinha (Lisbon), to the Academia Internacional de Cultura Portuguesa (Lisbon), as well as to the Portuguese Academy of Sciences.
He has received an Honorary Degree from the University of Aveiro, Portugal. João M. Brás edited a volume collecting writings on his work: Onésimo: Único e Multímodo (Opera Omnia, 2015) and a book on his works: Identidade, Valores, Modernidade: O pensamento de Onésimo Teotónio Almeida (Gradiva, 2015).
He teaches a Freshman Seminar "On the Dawn of Modernity" and a graduate course on science during the Portuguese maritime travels of the 15th and 16th centuries.