The Campus of International Excellence (CIE) initiative was launched in Spain in 2009. Among its objectives was to improve the position of Spanish universities in international rankings by 2015. The present work analyses the impact of CIEs on the ARWU-Shanghai Academic Ranking. The comparison between the average across the first three years of the CIE initiative (2009-11) and the last three (2013-15) reveals that the Spanish university system has notably improved its research performance, judging by the increase in average scores and the hike in positions. Universities coordinating CIE projects present a more stable evolution (an increase of 9% in scientific output) than those that don't (increase of 21%), resulting in a more homogeneous university system. Institutions with CIE projects comprising a single university achieve better positions in the rankings. Despite the context of the economic crisis, a tight timeframe and limited funding for the CIE initiative, the experience is found to have been positive in view of the evolution of Spanish universities in these rankings.