Brazilian historian best known for his large-scale interpretive work on Brazil's colonial history.

After serving at the National Library of Rio de Janeiro (1875–83), Abreu became professor of history at the Colégio Dom Pedro II in 1883. Influenced by the sociology of Auguste Comte and Herbert Spencer and the historical enterprises of Henry Buckle and Hippolyte Taine, Abreu wrote the Capítulos de História Colonial (1907; “Chapters of Colonial History”), his greatest work, as a broad study of Brazilian colonization from 1500 to 1800. His original emphasis on the culture of indigenous groups was an early and significant ethnological interpretation of the European settlement of Brazilian backlands. Abreu wrote additional works on linguistics, translated German and French documents on Brazilian history, and edited the writings of the eminent historian Francisco Adolfo de Varnhagen.