Oszkár Jászi was born in Nagykároly on March 2, 1875. His hometown was, as he put it in his unfinished memoirs, "the county seat of Szatmár, the center of a rich agricultural area, it was a major factor in Hungary's economic, municipal and political life." His father, Ferenc Jászi (1838–1910), was a family physician and (in his son's words) "an honorable, humane freethinker" who had had his family name changed from "Jakobuvits" to "Jászi" in 1881, a "typical symptom of the very strong and seemingly unqualified drive for assimilation that he and many Jewish contemporaries displayed around that time... This was the family climate that gave rise in the then six-year-old Oszkár to a self-image whereby for a long time thereafter he was simply unwilling to acknowledge his Jewish origins." The family also converted to Calvinism in the same year 1881.