Between each Population Census certain adjustments are made in the systems used to classify industries and occupations. During the planning operations for the 1960 Census, changes were made in the 1950 classifications systems so that the data would be more useful to census users. However, the modifications introduced complicate the work of those users who are interested in intercensal comparisons. It is to help these users that the present report, which describes in detail the adjustments made between 1950 and 1960, was prepared.