Zusammenfassung: Green technologies are at the very core of endeavors to combine economic and environmental targets to achieve sustainable growth. In this article, we aim to determine the impact of green technology development on total factor productivity of European regions. Our paper contributes to the literature on technological change and regional growth in various ways. i) Our paper is, to the best of our knowledge, the first to assess the specific role of green technologies for regional growth on a broad empirical base. ii) We advance methodologically on the pertinent literature by explicitly accounting for cross-sectional dependence in our empirical approach. iii) By providing a simple theoretical framework, we directly link our results to implications of environmental policies for capital accumulation and composition dynamics, contributing to the ongoing debate revolving around the strong version of the Porter hypothesis. Our results, based on a sample of 270 European NUTS-2 regions over 25 years, imply that general technology development is mostly associated with positive economic returns, but our data is not supportive of positive economic returns to green technologies.