[Editor's note: This article originally appeared at SocialFunds.com.]

Viewed through the lens of growth, 2010 can be seen as one in which sustainable investment moved closer to acceptance by the mainstream investment community, in the US and elsewhere.

By the end of the year, three reports detailing regional states of sustainable investment -- in Europe, the United States, and Australia and New Zealand -- had been published, and each showed that uptake of environmental, social, and corporate governance (ESG) factors in investment decision-making was on the increase. (Here are articles on the reports: Growth in Sustainable Assets Outpaces Mainstream, Sustainable Investment in Australia and New Zealand Outperformed Market in 2010 and Principles for Responsible Investment Publishes 2010 Report on Progress.)

Furthermore, the number of signatories to the United Nations' Principles for Responsible Investment (PRI) has grown to include over 800 signatories with a total of $22 trillion in assets under management. The number of new signatories since July 2009 now stands at 268, "evidence," the PRI states, "of the increasing recognition by institutional investors worldwide of the need to consider environmental, social and corporate governance (ESG) issues when investing."

Considering that many observers had cautioned that consideration of ESG factors by investors and corporations would decline in the wake of the financial crisis, such results are encouraging for practitioners of sustainable investment.

However, 2010 was a year in which the political winds in the US in particular turned sharply to the right, and the year's top stories indicate that the engagement practices of sustainable investors, both with companies and legislative and regulatory processes, will be if anything even more crucial in 2011. Here are the top five sustainable investment stories for 2010.

5. Congress passes health care reform legislation.

Despite the ongoing economic recession and high unemployment, President Obama maintained his priority of seeing health care reform enacted by Congress, and succeeded in the face of fierce opposition by most Republicans in Congress. In March, the House of Representatives passed the bill in a 219-212 vote, and a reconciliation bill passed the Senate afterward.

Sustainable investors have long made health care reform a central part of their mission. The number of shareowner proposals addressing health care reform increased considerably in the last two years, in an effort led by the AFL-CIO, which pointed out that access to affordable, comprehensive health care insurance is the most significant social policy issue in America.