Three broad themes are highlighted: (1) The analysis of linked employer-employee data. The basic finding of this and the next section is that the firm matters a good deal in explaining the differences in earnings, productivity, and work experiences of individual workers. Linked data allow the researcher to disentangle the firm effects from the worker effects. (2) Econometric issues involved with the analysis of such data. Creating and analyzing employer-employee matched data sets presents a number of new econometric problems