In 1979, Marc Nerlove and my doctoral advisor, Heinz König, launched a groundbreaking joint project on ‘Business Survey Data Analysis’, which continued for about 16 years. This project began during a period of transition in the economics profession, marked by a shift from macro theory to applied microeconomics, and from macro-econometrics to the study of qualitative micro data. Under the leadership of Nerlove and König, an international team pioneered the use of firm-level data for microeconometric analyses. This paper documents the team’s work, the challenges they faced, their ambitions, and their academic achievements. It also highlights Nerlove’s leadership, working style, and personality, as reflected in the project and beyond. As a member of the Mannheim research team, I also had the opportunity to become Nerlove’s academic guest at the University of Pennsylvania in 1987.