<p>This paper examines John R. Commons’ s relation to sociology. It puts forth the idea that sociology was at the heart of Commons’ s political economy, helping Commons frame his theory. Although this sociological influence may have been more substantial in Commons’ s early academic life, sociological knowledge has remained instrumental to Commons throughout his career. This paper exposes the underpinnings of this influence, putting forward the idea that Commons’ s framework can be captured through the concept of a ‘spiral theory’, in which sociology lied at this core.</p>