Polish-born Bogacki writes and illustrates a passionate picture-book biography of the Holocaust-era children’s advocate and doctor. Early Polish childhood life and interests quickly move into the doctor’s student days and expand to his renowned, democratically run orphanage. Korczak’s belief that children thrive when they are well cared for and learn to care for one another was the hallmark of his work. He steadfastly stayed with his children during the Nazi invasion and deportation and ultimately perished with them at Treblinka, but his legacy lives on. His defense of the rights of children is the forerunner of the established 1989 United Nations Convention on the Rights of the Child. And though this is a story that ends in dark despair, the author succeeds in creating a positive, upbeat atmosphere with his palette of muted reds, blues and greens, as opposed to that employed by Bill Farnsworth in David A. Adler’s A Hero and the Holocaust (2002), which was dominated by gloomy, dark-brown hues. (historical, author’s, source notes) (Picture book biography. 7-10)