This historical study examines the evolution of the accounting system of the Quincy Mining Company between 1846 and 1900. The external financial reporting practices and internal accounting procedures of the firm are defined and interpreted in the context of three time periods that portray the formation, growth and maturation of the firm. Each period reflects unique economic and social conditions that are associated with changes in the firm's accounting system. A cross temporal analysis of these changes highlights three factors: the relationship between the accounting system and the labor force, the emergence of accounting as a control mechanism and the diminishing informational content of the firm's annual reports. Primary sources are used to document the perspectives of the Quincy management and to assess the motivations for accounting processes such as internal control, auditing procedures, responsibility centers and other managerial practices. This study addresses the inherent nature of accounting information and its relationship to the economic and social environment of an individual firm in the nineteenth century.