One issue of considerable interest to managers is the relative importance of new and old plants in determining productivity growth. An analysis of the productivity performance of new entrants and long-term survivors over the last 30 years indicates that recent entrants have higher productivity than earlier entrants, surviving plants become more productive with age, and competitive forces lead to similar productivity of plants from different cohorts. (This report is part of a continuing series of occasional research reports that analyze historical patterns of productivity and growth in order to improve our understanding of the dynamics of the competitive process.)