This dissertation examines the relationship between Polybius Histories and the culture of the sciences in Hellenistic Greece. The period often is identified with noteworthy advances in scientific thought, not only in the extension of rational culture to broader and more diverse areas of inquiry, but also in the formalization of practices within and among fields of research. Historical writing may also be situated in this context, especially in light of comparable efforts to define and formalize study of the past as a more serious intellectual pursuit. With the great proliferation of historical texts at this time and especially the growth of concern for standards of historical method, the Hellenistic era is characterized by an increasingly stronger sense of historys status as a formal discipline. Polybius role in this set of developments is substantial; his writing is distinguished throughout by special concerns for methodology. In particular, it is the framework constituted by other forms of science, understood as a set of concrete models of description and analysis, which forms the basis for his approach. In this dissertation, I explain the practical and conceptual framework of contemporary science as a source of structure for this attempt to innovate in the historical field. My approach is based on three considerations, of which the first concerns factors internal to the historical field itself. Given the basic problems with knowledge of the past and especially the lack of clear standards for historical method, the historical field is typically characterized by dispute and rivalry among writers. As Polybius own interest in methodology is based on this largely routine set of concerns, his relationship with the sciences is to be understood primarily from the perspective of competition with existing sources of historical authority. Consideration of the Histories in relation to contemporary historical production thus reveals an effort to specialize study of the past on the basis of more stringent principles of historical reconstruction. Polybius approach is not arbitrary, but is based on formal approaches to inquiry employed elsewhere in the sciences, which, I argue, provide the basis for innovation in the historical field mainly due to the special cultural authority of such practices. Given the progress of Hellenistic science, technical adjustments in Polybius writing are to be understood in relation to current trends in the development of rational culture—the second main concern here. This detail not only clarifies the basis of Polybius critical engagement with the historical tradition, but also qualifies the relationship between history and the sciences in ancient Greece, a subject of controversy at least since Aristotle. The final part of my argument examines the consequences of this relationship for the production and organization of historical knowledge. Even as affiliations with the sciences provide the basis for a more serious approach to history e.g., as opposed to accounts of the past appearing in myth or in aristocratic genealogies), the same affiliations introduce constraints for historical representation as well. Thus the practices and concepts relating history to the sciences are not merely formal, but constitute a productive influence on constructions of historical perception. Overall, this project aims to provide a framework, formed on the model of Polybius Histories, for clarifying the relationship between the pragmatics of disciplinary development in the historical field and the organization of historical understanding more generally. The dissertation is divided into four chapters. In the first chapter, I provide an overview of ancient science by considering specific conditions governing the development of Classical and Hellenistic intellectual culture. Following modern theoretical approaches to the sociology of scientific knowledge, I examine the formation of certain research programs in this context as the expression of specific forms of social authority in intellectual culture. Chapter 2 examines Polybius concern for history as a source of technical instruction for the statesman. This aspect of his writing, denoted by the controversial expression pragmatike historia, reveals an effort to subject study of the past to concepts of knowledge and explanation employed in the practical sciences, which thus provide the model for a more useful account of political and military affairs. In Chapter 3, I extend a similar approach to Polybius concept of universal history. In the final chapter, I examine Polybius approach to the study of historical causes, most notably in his accounts of the various wars described in the Histories. This aspect of his writing is based on deliberate attempts to adapt methods of explanation in the natural sciences. In particular, I consider how use of that model extends the discourse on the origins of wars beyond conventional frames of concern in practical political contexts. Abstract shortened by UMI.)