She worked in France and Germany during and after World War I, and founded the Jewish Nurses' Training School in Warsaw in 1923.

[7] The program addressed rural women's health broadly, including English lessons, a resource library, and hygiene classes.

[4][8] During World War I, Greenwald went to France with the American Red Cross, and worked in hospitals at Verdun and Savoy, as well as in Koblenz in Germany.

[11][12] "There is no force in Poland which will act as an agency for good as will this group of girls who are going into homes, spreading knowledge and raising the standards of the people", she said in 1927, of the Polish nurses her school trained.

[4] Greenwald received a Victory Medal for her services in World War I, and the Polish Golden Cross of Merit for her work in Warsaw in the 1920s.