The history of the socialist movement in Brazil is generally thought to trace back to the first half of the 19th century. There are documents evidencing the diffusion of socialist ideas since then, but these were, however, individual initiatives with no ability to form groups with actual political activism.
In 1892 the First Socialist Congress of Brazil occurred in Rio de Janeiro. Later that year, in São Paulo, another Socialist Congress, independent from the latter, took place. That same year the Workers' Socialist Party (Partido Operário Socialista) was founded in Rio de Janeiro. This is considered to be the first socialist party in Brazil. In 1895, also in Rio, the Socialist Workers Party (Partido Socialista Operário) was founded. That same year, Silvério Fontes, considered the first Brazilian Marxist, launched the Socialist Center of Santos, which soon published the socialist magazine A Questão Social (The Social Question) and newspaper O Socialista (The Socialist).
The first major socialist party of the country was founded in 1902 in São Paulo, under the auspicious of Italian immigrant Alcebíades Bertollotti, who was once responsible for Avanti, the official newspaper of the Italian Socialist Party. That same year, the Socialist Collective Party (Partido Socialista Coletivista) was founded in Rio de Janeiro, headed by Vicente de Sousa, a teacher at the , and Gustavo Lacerda, a journalist and founder of the Brazilian Press Association (Associação Brasileira de Imprensa – ABI). In 1906, the Independent Workers Party (Partido Operário Independente) was founded; it created a "popular university", which had , , and as teachers.
The diffusion of socialist ideas increased during the First World War, but most of the Brazilian left-wing groups were still alienated from the general public. In June 1916, Francisco Vieira da Silva, Toledo de Loiola, Alonso Costa, and Mariano Garcia launched the Manifesto of the Brazilian Socialist Party (Manifesto do Partido Socialista Brasileiro). On May 1st of the following year, the Manifesto of the Socialist Party of Brazil (Manifesto do Partido Socialista do Brasil) was launched, signed by Nestor Peixoto de Oliveira, Isaac Izeckson, and Murilo Araújo. This group launched Evaristo de Morais to the House of Representatives and published two newspapers, Folha Nova (The New Leaf) and Tempos Novos (New Times), both short-lived.