This chapter addresses the pathway to the enforcement of sustainability by private subjects. Going for sustainability while engaging with CSR can create costs but, as well, anti-sustainability behaviour, including CSI, can create costs. Therefore, stakeholders, especially the almighty investors, need to be informed so that they can make educated decisions and become powerful, effective and efficient enforcers of sustainability at the private law level. Investment decisions have always focused on the likelihood (risk) and rate of return in the financial sense, but almost never on that alone. Indeed, the reasons for investment have always been heterogeneous and often political. Other considerations could even overshadow a simple rate of return calculation. However, a systematic linking and tying of sustainability projected into CSR to investment has a history of only half a century (Sect. 9.1) while just two decades ago there began the discussions about how, i.e. whether, the market self-regulation could lead to the very needed ranking via ESG scoring and indexes (Sect. 9.2). Finally, similar to CSR, the last stage came in 2015 and this means the UN standardization (Sect. 9.3), which developed particularly under the auspices of the EU law (Sect. 9.4)