In this paper we use panel data on NUTS 1 regional data for 27 EU countries in the years 2006-2010 to analyze determinants of broadband diffusion. We estimate both linear demand specification and the logistic diffusion function. We find that, after controlling for regional differences due to socioeconomic factors, inter-platform competition approximated by an inter-platform Herfindahl index has a significant positive impact on broadband diffusion. Broadband deployment is lower in countries in which DSL has a greater share in Internet access and it is higher in countries in which cable modem has a greater share in Internet access. Moreover, we find that competition between DSL providers has a significant and positive impact on broadband penetration. First, higher prices for a fully unbundled local loop connection, which represent the cost of providing copper-based Internet services, have a significant and negative impact on broadband penetration. Second, a greater incumbent share in DSL connections has a significant and negative impact on broadband penetration.