The article uses time series for the period 1981-2008 to estimate the impact of foreign technology spillover effects on Greece, Ireland, Portugal and Spain, representing the integrating European Union (EU) countries. I restrict technology diffusion to EU-12 countries and compare the results to unrestricted technology diffusion from a sample of 32 OECD countries. Accounting for nonstationarity and co-integration, the dynamic OLS estimator is used to estimate the impact of foreign R&D stock on labour productivity, taking into account patent-, trade-and FDI-related technology diffusion channels. I find empirical evidence for traderelated foreign technology spillover effects for Greece and Ireland if technology diffusion is unrestricted. Restricting technology diffusion to EU-12 countries, there are significant foreign technology spillover effects from European integration for Portugal (patent related) and Spain (trade and FDI related). Moreover, the domestic R&D stock and education are significant drivers for labour productivity in integrating EU countries. The empirical results are robust for different regression specifications and sources of technology diffusion.