From 2010 until its closure at the end of 2024, the Sustainable Investments Institute (Si2) operated as a non-profit organization based in Washington, D.C. Inspired by the Investor Responsibility Research Center, which operated independently from its founding in 1972 until 2005, Si2 conducted impartial research and published reports on organized efforts to influence corporate behavior on social and environmental issues.

Si2 closely followed shareholder resolutions proposed by investor activists, analyzing changing reform campaigns and identifying key points of contention in reports to help investors make informed, independent decisions about their votes and views on these proposals. It also published related reports for the public on related topics. Working as a non-aligned group differentiated Si2 from other companies, activists and researchers since it did not advocate for specific solutions but sought to build a body of agreed knowledge for smart policy-making.

This archive at US SIF opens up Si2's proprietary database of more than 7,200 shareholder proposals filed by investors to the public, to further Si2's mission. The archive also includes all the detailed reports Si2 published on shareholder proposals that went to votes, alongside all the annual in-depth briefing papers on the issues, as well as pre- and post-season analysis. Si2's special reports funded by grants over the course of its existence also are included; many were generously funded by the IRRC Institute, whose publications now are archived its work at the Weinberg Center for Corporate Governance at the University of Delaware