Erich Walter Zimmermann (July 31, 1888 – February 16, 1961) was a resource economist. He was an economist at the University of North Carolina and later the University of Texas.

Zimmermann of the Institutional school of economics^[1] called his real world theory the functional theory of mineral resources. His followers have coined the term resourceship to describe the theory.^[2] Unlike traditional descriptive inventories, Zimmermann's method offered a synthetic assessment of the human, cultural, and natural factors that determine resource availability.

Zimmermann rejected the assumption of fixity. Resources are not known, fixed things; they are what humans employ to service wants at a given time. To Zimmermann (1933, 3; 1951, 14), only human "appraisal" turns the "neutral stuff" of the earth into resources.^[3] What are resources today may not be tomorrow, and vice versa. According to Zimmermann, "resources are not, they become."^[4] "According to the definition of ew Zimmerman, the word ,"resource " does not refer to a thing but to a function which a thing may perform to an operation in which it may take part,namely,the function or operation of attaining a given end such a satisfying a want.

• “Resources of the South”, The South-Atlantic Quarterly (July 1933)
• World Resources and Industries: A Functional Appraisal of the Availability of Agricultural and Industrial Resources (1933) New York: Harper & Brothers
• World Resources and Industries, 2nd revised ed. (1951) New York: Harper & Brothers