One of the largest public employee pension funds in the USA is the California State Teachers’ Retirement System (CalSTRS), which has US$160 billion in Assets Under Management and serves 800,000 beneficiaries.  As the fund managers say, “We have an obligation to be responsible stewards of the retirement funds of California’s educators.”  And corp gov activists they are!
That includes being an activist and engaged institutional investor and focusing on issues [critical to fund managers] when CalSTRS engages with companies in the investment portfolio. The fund just issued  its very first Corporate Governance Annual Report (2013), which explains investment policies, governance philosophy, partnerships (example, with the Council of Institutional Investors/CII, the fund’s trade association; Ceres; UN Principles for Responsible Investment/PRI, of which CalSTRS is a signatory,  Investor Network on Climate Risk/INCR, a project of Ceres); and an explanation of corporate engagements.
Issues in focus for corporate engagement discussions include Exec Comp, Say on Pay; Majority Vote Standards; Diversity of Boards; and (of course) Sustainability.  The fund is an activist in filing and supporting other investors’ sponsored shareholder resolutions at proxy voting time.
In 2012 CalSTRS voted nearly 7,000 meetings — 3,000 U.S.A. and 4,000 non-US companies in portfolio.  Some 24,000 proposals were considered for the US companies and double that for non-US companies. 
CalSTRS believes that “good governance contributes to better long-term sustainable performance. Asset managers hired by CalSTRS take large positions in companies and are required to be active in engaging with boards and senior management to “undertake value-driving change…” Eight partnerships with asset managers are identified in the report.
This is a good primer if you are interested in learning more about what large US activist pension funds are focusing on in both the traditional governance and (newer) sustainability areas.  It’s available on line at the CalSTRS web site: http://www.calstrs.com/news-release/calstrs-releases-first-annual-corporate-governance-report
P.S.
Matthew Scott, Editor of Corporate Secretary in his timely and information email newsletter is informing his audience of influencers – corporate secretaries – of the CalSTRS governance report and suggesting that this is one way for board governance influential to better understand the large public fund’s focus on corporate engagements. He characterized the report as “a definitely a positive development for the corporate governance industry…”)  You can contact Matthew at Corporate Secretary magazine (Cross Border Publications) and follow him on Twitter – @corpsecmag