From then until he left for the US in 1934, he was employed by the German statistical office and the Institut fur Finanzwesen, working on studies of the banking and economic systems of Latin America and elsewhere.
At the Department of State, he helped devise the Colm-Dodge-Goldsmith plan for the German currency reform of 1946, and the financial implementation of the 1947 Austrian peace agreement.
This work, partly coauthored with Dorothy Brady and Horst Menderhausen, ran to three volumes totalling more than 2000 pages and included many hundreds of tables of time series data.
Goldsmith is mainly known as the author of about 15 scholarly books, immensely rich in historical economic and financial data about the US, other countries, and the ancient world.
His method for estimating Roman GDP from meager ancient evidence provided the basis for subsequent attempts by economic historians such as Angus Maddison, Peter Temin and others.