American forces entered a seemingly dangerous and very foreign world following the surrender of Japan. A nation-building mission unlike any other previously in U.S. history ensued. Insight into Japanese sentiment and ways of conducting business would be paramount to the success of General Douglas MacArthur in demilitarizing and democratizing Japan. Two complementary but rival organizations within MacArthur’s Supreme Commander for the Allied Powers (SCAP) staff were created and charged with understanding Japanese thought patterns and culture to assist with successful reform. The Research and Analysis Branch (R&A), subordinate to the Civil Intelligence Section (CIS), was responsible for turning out quality anecdotal intelligence analysis. It produced weekly “Occupational Trends” reports critical to monitoring Japanese sentiment on issues of seminal importance to demilitarization, such as Japanese popular opinion concerning the maintenance of the Emperor. The other organization, the Public Opinion and Sociological Research Division (PO&SR) under the Civil Information and Education Section (CI&E), employed social scientists who worked closely with Japanese nationals on democratization. For perhaps the first time in history, sociological research supplemented traditional intelligence analysis in informing occupational leaders. PO&SR prepared scientific socio-cultural reports that served various sections across MacArthur’s government. While rivalries existed between the R&A and PO&SR over methods and utility of services, the framework established under the occupation serves as a model of how to process and produce foreign socio-cultural intelligence and research during nation building. Analytic lessons learned include encouraging close cooperation between intelligence professionals and more specialized sociologists, incorporating diverse collection sources, working closely with host nationals, and formally documenting social science project findings.