For its scope and the breadth of its available resources, the university system is one of the keys to implementing and propagating policies, with sustainability policies being among them. Building on sustainability performance in universities, this study aimed to: Identify the procedures deployed by universities to measure sustainability; detect the strengths and weaknesses of the Spanish university system (SUS) sustainability practice; analyse the SUS contributions to sustainability-related Research, Development and Innovation (R&D+I); and assess the efficacy of such practices and procedures as reported in the literature. The indicators of scientific activity were defined by applying scientometric techniques to analyse the journal (Web of Science) and European project (CORDIS) databases, along with reports issued by national institutions. The findings showed that measuring sustainability in the SUS is a very recent endeavour and that one of the strengths is the university community’s engagement with the ideal. Nonetheless, high performance is still elusive in most of the items analysed. Whereas universities account for nearly 90 % of the Spanish papers published in the WoS subject category, Green and Sustainable Science and Technology, their contribution to research projects is meagre. A divide still exists in the SUS between policies and results, although the gap has been narrowing in recent years.