From a simple idea to unite asset owners in their quest for responsible investment (RI) at its launch in April 2006, the United Nations supported Principles for Responsible Investment (PRI) have grown in just one decade into an initiative with more than 1500 fee-paying signatories. Jointly, the PRI's signatories hold assets worth more than $80 trillion, making it one of the more prevalent not-for-profit organizations worldwide. Furthermore, the PRI's ambitious mission to transform the financial system at large into a more sustainable one makes it a worthwhile subject of inquiry from an institutional perspective. We undertake an empirical investigation of the adoption of the PRI by asset owners during five crucial years of the association's emergence: 2007-2011. Following a tripartite view of institutional theory proposed by Scott (Institutions and organizations. Foundations for organizational science, A Sage Publication Series, London, 1995), we explore if regulative, normative, and cultural-cognitive factors influence an asset owner's decision to subscribe to the PRI. Applying both parametric and nonparametric survival analysis, we find that asset owners are indeed significantly affected by normative, cultural-cognitive, and regulative aspects. In particular, (i) public service employee and labor union pension funds (ii) from social backgrounds more culturally aligned with values represented by the RI movement (iii) with historically more voluntary legislation on environmental, social, and governance (ESG) issues are most likely to sign the PRI. In contrast, institutional environments with a higher number of pre-existing mandatory ESG regulation decrease the likelihood of signing the PRI. Our results indicate that normative and cultural-cognitive factors were crucial contributors to the PRI's growth. With respect to the regulative environments, our results imply that some asset owners may use the PRI as a collective industry initiative to substitute for mandatory legislation. Conversely, a high level of historical mandatory legislation may constrain organizational resources that could otherwise be dedicated to voluntary initiatives such as PRI. Our findings are robust to relevant controls and econometric concerns.