Casais Monteiro graduated in History and Philosophy at University of Porto (Faculdade de Letras), where he was colleague of Agostinho da Silva and Delfim Santos, in 1933. At Porto he started as a high school teacher at Liceu Rodrigues de Freitas, until he was prevented from teaching by the government dictatorship in 1937. He would eventually go into exile in Brasil in 1954 for the same reasons.
After the removal of Miguel Torga, Branquinho da Fonseca and Edmundo de Bettencourt, in 1930, Adolfo Casais Monteiro was director of the Coimbra's literary journal Presença (journal), with José Régio and João Gaspar Simões. This journal published the political views of Casais Monteiro until it ceased publication in 1940. He was arrested several times due to his political opinions adverse to the Estado Novo regime and directed anonymously the weekly Mundo Literário in 1936 e 1937.
Prevented from teaching, Casais Monteiro goes to Lisbon, living as literary author, translator and editor. As Agostinho da Silva or Jorge de Sena, he would eventually leave to Brasil, due to his opposition to Estado Novo, which he could not accept. He also directed the journal Princípio (1930) and collaborated with the journals Sudoeste (1935) and Variante (1942–43).
Having participated in the celebrations of the 4th centenary of Cidade de São Paulo, in 1954, Adolfo Casais Monteiro fixed residence in Brasil, teaching since then Portuguese Literature in several Brazilian universities, namely at Universidade da Bahia in Salvador, till fixed in 1962 at Universidade Estadual Paulista (UNESP), Campus de Araraquara-SP. He wrote by then several essays and wrote as literary critic for several Brazilian newspapers, having contributed to the study of Fernando Pessoa and the Movimento da Presença.
Among his translations works is Germania, de Tacitus, published in 1941. His only novel, Adolescentes (Teenagers), was published in 1945.
His poetic work, which began in 1929 with "Confusão", was influenced by the first Portuguese modernism, approaching stylistically aestheticism of André Gide. Their criticisms of concreteness were based on the idea that this aesthetic movement promoted impersonality, starting from the "'purest abstractions to build a new language to the service of nothing, a pure language, an invention of objects - in short: a beautiful toy". "While some authors describe it as independent of Surrealism others emphasize the influence that this had on the author's current aesthetic, as can be seen in his essays on authors such as Jules Supervielle, Henri Michaux e Antonin Artaud (designating the latter as unsustainable presence ). Much of his poetry is dedicated to the specific historical period in which he lived, as in the poem "Europa", de 1945, which was read by his friend and colleague António Pedro in Literary World at the microphones of London BBC.
Married Mary Alice Pereira Gomes, also a writer and sister of Soeiro Pereira Gomes, with whom he had a son.Confusão - 1929
Correspondência de Família (with Ribeiro Couto) - 1933
Poemas do Tempo Incerto - 1934
Sempre e Sem Fim - 1937
Versos (comprises the 3 previous books) - 1944
Canto da Nossa Agonia - 1942
Noite Aberta aos Quatro Ventos - 1943
Europa - 1946
Simples Canções da Terra - 1949
Voo sem Pássaro Dentro - 1954
Poesias Escolhidas - 1960
Poesias Completas - 1969
Adolescentes - 1945
A Educação Sentimental - Gustave Flaubert - Reedited by Editora Nova Alexandria, 2009.
Considerações Pessoais - 1935
A Poesia de Ribeiro Couto - 1935
A Poesia de Jules Supervielle - 1938
Sobre o Romance Contemporâneo - 1940
De Pés Fincados na Terra - 1941
Manuel Bandeira - 1944
O Romance e os seus Problemas - 1950
Fernando Pessoa e a Crítica - 1952
Fernando Pessoa, o Insincero Verídico - 1954
Problemas da Crítica de Arte (A Crítica e a Arte Moderna) - 1956
Estudos sobre a Poesia de Fernando Pessoa - 1958
A Poesia da Presença (with un anthology) - 1959
Clareza e Mistério da Crítica - 1961
O Romance (Teoria e Crítica) - 1964
A Palavra Essencial - 1965
A Literatura Popular em Verso no Brasil - 1965
Estrutura e Autenticidade como Problemas da Teoria e da Crítica Literárias - 1968
O País do Absurdo - 1974
O que foi e o que não foi o Movimento da «Presença» - 1995
Melancolia do Progresso - 2003
Cartas Inéditas de António Nobre (Introduction and notes from ACM) - 1933
Cartas em Família - 2008
Cartas a Sua Mãe - 2008