An evolutionary perspective, which is currently enjoying a revival in the social sciences, raises the possibility of a major transformation in the study of political development and modernization. It may be desirable to supplement (and in some instances replace) the concept of “political development” with the concept of “political evolution.” Political development may be likened to the biological process of ontogeny. It involves the construction of a viable set of political qua cybernetic processes and structures at any level of social organization, from wolf packs to human families to empires. Political evolution is an aspect of phylogeny. It involves the invention, elaboration, and diffusion of novel political forms of all kinds, only some of which may be more effective, or inclusive, or democratic, etc. Nor are all evolutionary changes necessarily “better” (i.e., more adaptive). Political development is concerned with problems of social engineering, while political evolution is concerned with architectonics—with the emergence of functionally significant political innovations. Political development is always situation-specific, while political evolution is also historical and may include changes that diffuse and become “species-wide.” Political evolution is thus a dimension of the larger process of biological evolution. The emergence of political systems, which long predates the evolution of humankind, constitutes a set of adaptive strategies with significant evolutionary consequences. Political development and political evolution may go hand in hand, but this is not always the case. A particular polity may develop or decay independently of the larger process of political evolution. Among the many theoretical implications of this conceptual reformulation, we briefly address the impact on functionalist theory, modernization theory, social mobilization theory, political economy (positive theory), world systems theory, dependency theory, and contemporary Marxist views.