We analyze the dynamics of worker mobility in the United States over the 1968-1993 period at various levels of occupational and industry aggregation. We find a substantial overall increase in occupational and industry mobility over the period and document the levels and time trends in mobility for various age-education subgroups of the population. To control for measurement error in occupation and industry coding, we develop a method that utilizes the newly released, by the Panel Study of Income Dynamics, Retrospective Occupation-Industry Supplemental Data Files. We emphasize the importance of the findings for understanding a number of issues in macro and labor economics, including changes in wage inequality, productivity, life-cycle earnings profiles, job stability and job security.