Wohlstetter started at Columbia Law School on a fellowship in 1934. It was in a class there that he met Roberta Morgan. Wohlstetter was bored by law school and left the program after only one year. He stayed at Columbia to pursue a Ph.D. in mathematical logic and the philosophy of science where he studied under Abraham Wald and was a peer of Jacob Wolfowitz. After a thesis titled "Language and Empiricism" earned him an M.A. in June 1937, several fellowships allowed him to work on his dissertation. He had a fellowship with the Social Science Research Council on a project to incorporate modern mathematical methods into economics and business cycle research. From 1941–1942 he was a research associate at the National Bureau of Economic Research.