The article examines the traditional body of knowledge about enterprise resources and presents contemporary approaches to this issue. The author uses ample theoretical material and describes historic views on enterprise resources as expressed by economists such as Petty, Smith, Ricardo, Say, Marx, Marshall, the Austrian Subjectivists, Schumpeter and Penrose. Their achievements laid the groundwork for contemporary research. The author focuses on the ways in which enterprises build their competitive advantages. He also presents contemporary approaches and resource classification systems, with special attention paid to non-material resource classification, including the resource theory and the intellectual capital theory (pioneering and post-pioneering models). The analysis shows that non-material resources and intellectual capital are increasingly important to enterprises as they seek to gain a competitive advantage. This marks a change from previous approaches to the problem of building a competitive advantage. However, the contemporary method of defining enterprise resources is rooted in the historic development of economic knowledge. It is the legacy of many well-known authors, from classical economists onward. Their achievements were an inspiration for contemporary economists.