This chapter showcases how sustainable development and CSR clauses are included in international investment agreements, throughout a timeframe of eleven years, from 2013 to 2023 included. The analysis is based on the availability of the documents and it is conducted on preambles and body of the agreements separately, analyzing the different hard or soft formulations that express both types of clauses. The study finds that there is a consistent, albeit not progressively increasing, presence of CSR clauses in both the body and the preamble of international investment agreements but with different trends in terms of the source of CSR (whether internationally recognized or recognized by the parties) and its explicit relation to sustainable development. Sustainable development, on the other hand, is consistent in the preambles of the agreements, but not in the bodies of the agreements, where its inclusion is novel and rare. It is not always necessarily framed as a self-standing objective, which may give rise to interpretative misgivings.