Stefania Wilczyńska (1886–1942) was Korczak's co-director at Dom Sierot for thirty-three years, the longest and most consequential professional partnership of his life. Trained in natural sciences, she joined the orphanage in 1909 — three years before Korczak — and remained its operational spine until its liquidation in 1942. Where Korczak was the public face of the institution (author, lecturer, broadcaster, theoretician), Wilczyńska was the daily practitioner. She handled logistics, personnel, the constant negotiation with donors and authorities, and the minute-by-minute work of keeping the orphanage functioning. Accounts by former orphans consistently identify her as the figure whose steady presence they remembered most vividly. She refused multiple offers of personal escape — including, reportedly, emigration to Palestine — and walked to the Umschlagplatz alongside Korczak and the children on August 5 or 6, 1942. She was murdered at Treblinka with them.
Wilczyńska's contribution to Korczak's framework has been systematically under-acknowledged in accounts that focus exclusively on Korczak. The institutional practices