The creation and growth of publicly accessible data archives (or data banks) have revolutionized the way sociologists conduct research. These resources have made possible a variety of secondary analyses, often utilizing the data in ways never anticipated by their creators. Traditionally, secondary data analysis involves the use of an available data resource by researchers to study a problem different from the one treated in the original analysis. For example, a researcher might have conducted a survey of workers' reactions to technological change and analyzed those data to evaluate whether the workers welcomed or resisted such change in the workplace. As a matter of secondary interest, the researcher collects data on workers' perceptions of the internal labor-market structures of their firms. She then lends those data to a colleague who studies the determinants of (workers' perceptions of) job-ladder length...