For all types of OECD regions, human capital appears to be the most critical and statistical robust factor influencing regional grow'th and development. The cross-regional analysis finds that, overall, reducing the proportion of the people in a region with very low skills seems to matter more than increasing the share with very high skill levels. Furthermore, the gains to human capital are multiplied when other framework conditions in the regions are in place, which indicates the importance of adopting a broader holistic approach to regional development.