NEW YORK (CNNMoney.com) -- In a world full of vice and guilty pleasure, investors can rest assured that when it comes to their investments, at least there's one area in their lives where having a conscience can produce hefty returns.

Socially responsible investment (SRI) funds have seen massive growth over the last ten years, providing virtuous investors with returns that are comparable to, if not better, than traditional funds - debunking a common myth among financial advisors that screened funds can limit returns for investors.

To qualify as a socially responsible fund, investments must meet certain criteria. Generally, SRI funds steer clear of companies that aren't environmentally friendly, are involved in nuclear technology, sell weapons, tobacco or liquor products or promote gambling, said Robert Thomas, founder and president of Social(k), a 401(k) retirement platform that specializes in socially responsible funds.

Some funds also focus on specific social issues including women's empowerment, human rights and corporate governance.

Despite the seemingly narrow scope, the number of SRI funds available in the market have jumped over 300 percent since 1995. Investors can choose between 221 SRI funds, up from an offering of 55 available funds just 10 years earlier.

According to a study by the Social Investment Forum, a national trade association for SRI professionals and funds, socially responsible investment assets jumped 258 percent to $2.29 trillion in 2005 from $639 billion in 1995.

By comparison, the broader universe of assets under management climbed less than 249 percent to $24.4 trillion from $7 trillion over the same period.

In a post-Enron environment, part of the attraction for investors is the heavy focus on corporate governance within SRI funds.

SRI funds avoided companies like Enron and WorldCom before scandal struck - largely due to poor corporate governance concerns - providing some cushion against the market meltdown that hit Wall Street. That sparked interest among investors.

"When investors saw scandals hit one after another, there was a positive inflow of assets (in SRI funds) which are more active on corporate governance issues," said Todd Larsen, media director at Social Investment Forum.

But since then, Larsen said SRI funds have become more mainstream as investors realized that they didn't have to sacrifice returns in order to listen to their social conscience.

Social(k)'s founder Thomas added that investors increasingly began to demand that employers offer more SRI funds as part of their 401(k) plans, increasing the inflow of assets to this class of funds.

With 221 funds to choose from, here are some solid performers to consider:

This environmentally-friendly, aggressive growth fund seeks out domestic small-and mid-sized companies that are involved with renewable energy, natural and organic food, healthcare and consumer products among other industries. Among the companies top holdings are Zoltek Companies (Charts), a producer of carbon fiber that is used to manufacture blades for wind turbines, and biopharmaceutical firm Arena Pharmaceuticals (Charts).

The fund measures its performance against the Russell 2000 Growth index - a benchmark that it has solidly outperformed over the last 10 years. As of March 31, the fund is up 19.6 percent since the beginning of the year as compared to the Russell 2000 Growth Index, which has gained 14.3 percent. On a 12-month basis the Winslow Green Growth fund posted returns of 46.3 percent while the Russell 2000 Growth Index gained 27.8 percent.

This five-star Morningstar rated fund is part of the Calvert family of socially responsible funds. The fund doesn't discriminate between value and growth stocks but its pro-green stance keeps it free of companies that have poor environment records, such as regulatory compliance and waste management issues. It also screens companies for those that have strong corporate governance and have a history of solid employment practices and above-par human rights records.

Among its top holdings are corporate giants like Goldman Sachs (Charts) - known for its environmental efforts - as well as Bristol-Myers Squibb (Charts) and Hewlett-Packard (Charts).

While the funds is down 0.66 percent, underperforming its benchmark S&P 500 Index, the Calvert Large-Cap Growth fund gained 11.1 percent in 2005, outperforming the S&P 500 by 6 percent, according to Morningstar.com.

For those interested in a socially conscious alternative to stocks, the Calvert Social Bond fund fits the bill. 64 percent of the fund is invested in corporate bonds with a top AAA rating - providing a hedge against credit concerns for investors.

The fund invests in securities issued by by corporations, governments and government agencies but will only look at candidates that pay close attention to strong governance and ethics and are dedicated to the environment, workplace issues, product safety international operations, human rights, indigenous peoples' rights, and community relations.

Year-to-date, the fund is down modestly but in 2005, the Calvert Social Bond fund posted returns of 4.5 percent, according to Morningstar.com.

This global fund seeks environmentally-friendly international corporations that also show rising revenue and earnings trends, increasing profit margins and innovative, evolving products. Corporations that have poor histories of employee relations, human rights, community involvement, or product safety need not apply.

Given its international bent, the fund counts companies such as Nokia (Charts) among its top holdings and recently added IBM (Charts) to its top five holdings. In the first quarter of 2006, the fund gained about 10.1 percent, outperforming the MSCI World Equity Index, which posted a 6.72 percent gain. And on a 12-month basis, Portfolio 21 was up 19 percent as compared to an 18.6 percent gain on the MSCI index.

The Women's Equity fund is focused around female empowerment in the workplace. The fund looks for corporations that advance the social and economic status of women by promoting women to top executive positions, maintaining a work-life balance and and present women in a positive light through its advertising and marketing campaigns. The criteria is based on the assumption that firms that recognize and encourage their female talent also tend to be socially conscious in their businesses given the influence of the women within their organization.

The fund is a large-cap blend that counts companies such as energy firm BP PLC (Charts) and banking giant Bank of America (Charts) among its top holdings. While the fund has underperformed the S&P 500 over the past two years, Morningstar analyst Todd Trubey said in a recent research note that the underperformance was related to its contrarian positions in healthcare and financial stocks - both industries that suffered some weakness last year but should be good long term bets.

----------------------------------------------------------

Related: Investors bet on their faith