Extract: This paper examines the relationship between market structure and four aspects of operational efficiency in food and tobacco manufacturing from 1958 to 1977. While controlling for industrial and labor characteristics, it was found that the more concentrated product classes paid the highest average hourly wages in each year of the study, have shown the largest increases in these earnings over time, and have demonstrated higher increases in unit labor cost than the less concentrated product classes. Finally, it is shown that productivity increases were not higher in the concentrated sector than in more competitive markets.