This paper investigates whether specialization in research is causing economics to become an increasingly fragmented and diverse discipline with a continually rising number of niche-based research programs and a declining role for dominant cross-science research programs. It opens by framing the issue in terms of centrifugal and centripetal forces operating on research in economics, and then distinguishes descriptive from normative pluralism. It reviews recent research regarding the JEL code and the economics’ J. B. Clark Award that points towards rising specialization and fragmentation of research in economics. It then reviews five related arguments that might explain increasing specialization and fragmentation in economics: (i) Smith’s early division of labor view, (ii) Kuhn’s later thinking about the importance of specialization, (iii) Heiner’s behavioral burden of knowledge argument, (iv) Ross innovation-diffusion analysis and Arthur’s theory of technological change as determinants of specialization in science, and (v) the effects of space and culture or internationalization on innovation appropriation. The paper then discusses what descriptive pluralism implies about normative pluralism, and makes a case for multidisciplinarity over interdisciplinarity as a basis for arguments promoting pluralism. The paper closes with brief comments on the issue of specialization and pluralism in the wider world outside economics and science.