Julian Simon famously argued that economic growth is correlated with population growth. The basis for this correlation is what Simon refers to as the “ultimate resource,” namely the human mind and the collective stock of dispersed, tacit, and inarticulate knowledge among individuals. Though not incorrect, this simple rendition of his argument does not do full justice to the inspiration that Simon took from the mainline of economic thought. The purpose of this paper is to situate Julian Simon’s The Ultimate Resource as part of the mainline of development economics. I do so by developing an implicit and underappreciated relationship between entrepreneurship and economic growth in Simon’s The Ultimate Resource. I argue that this correlation between economic growth and population growth is predicated on what Simon refers to as “economies of scope.” This implies twofold. First, that a Smithian division of labor and a Hayekian division of knowledge emerge simultaneously, but are inherently predicated on a Misesian division of private property rights. Secondly, population growth is a proximate cause of economic growth, and therefore a by-product of a more fundamental institutional foundation: an ever-increasing scope in the ability of individuals to exchange ideas, goods, and services.