Content and Language Integrated Learning (CLIL) represents an increasingly popular pedagogic approach that has evolved in response to the recognised need for plurilingual competence in Europe. In this article, we present key findings from one of the first large-scale, multidimensional CLIL evaluation projects. We begin by outlining the emergence of European CLIL and by comparing it with other, non-European bilingual education initiatives and then we narrow the scope to Southern Spain, where the research was conducted. We outline the Andalusian Bilingual Sections programme, one of the cornerstones of the government's "Plurilingualism Promotion Plan" (2005), within which the research was conducted. In presenting results, we focus on specific areas that we believe make significant contributions to some of the key concerns in contemporary CLIL research including the linguistic competence of CLIL learners, the question of starting age, the distribution and functionalities of L2 use in CLIL classrooms, and the ways in which CLIL appears to be impacting on the educational system in general.