In 1912 Korczak established a Jewish orphanage, Dom Sierot, in a building which he designed to advance his progressive educational theories. He envisioned a world in which children structured their own world and became experts in their own matters. Jewish children between the ages of seven and fourteen were allowed to live there while attending Polish public school and government-sponsored Jewish schools, known as “Sabbath” schools. The orphanage opened a summer camp in 1921, which remained in operation until the summer of 1940.
Besides serving as principal of Don Sierot and another orphanage, Nasz Dom, and working as a doctor and an author, he also worked at a Polish radio station, was a principal of an experimental school, published a children’s newspaper, and was docent at a Polish university. Korczak also served as an expert witness in a district court for minors. With the rise of anti-Semitism in the 1930s his activities were restricted to Jews.
In 1934 and 1936 Korczak visited Palestine and was influenced by the kibbutz movement. Following his trips, Korczak was convinced that all Jews should move to Palestine. During the Second World War he was imprisoned for his refusal to wear the yellow star. Although offered asylum, he refused to abandon his orphans and went to the Warsaw ghetto with them. There he created a cultural centre which held literary evenings and where the children gave performances.