After returning to the US, in 1920 Schultz married to Bertha Greenstein. In the future years, the couple had two daughters, Ruth and Jean. Schultz continued studying for his doctoral degree at Columbia, while at the same time conducting statistical work for the War Trade Board, the United States Census Bureau and the United States Department of Labor. He was awarded a PhD in economics from Columbia in 1925 with a thesis entitled "Estimation of Demand Curves", written under the supervision of Henry L. Moore.