Regional mobility in the spatial distribution of per capita income in the European Union is examined over the period 1977 to 1999. The methodology used to investigate this issue combines a series of measures taken from the literature devoted to the dynamic study of personal income distribution with a non-parametric analysis. The results show limited mobility in the distribution considered, and a decline in mobility over time. The empirical evidence presented indicates, moreover, that mobility patterns vary as a function of regional development levels. Additionally, the analysis carried out investigates the role played in explaining intra-distribution mobility by variables such as per capita income, population density, per capita expenditure in investment, market potential, and the share in total employment of agriculture, advanced services and non-market services.