The paper describes a cross-sectional regression analysis for fourteen manufacturing orders of the factors explaining industrial mobility, the share of movement going to the development areas, and overall employment performance in the development areas relative to the nation (measured as the differential shift). Explanatory variables included national growth, plant size, labour force composition, and capital intensity. Two main time periods were studied: 1952-60 when regional policy was weak and 1960-71 when policy was strong. Sub-period results for 1960-71 were used to examine the effects of the changes in regional policy instruments, particularly the regional employment premium.