Most people can identify the S&P 500 stock index as one of the broadest based stock market barometers. But are you familiar with the Domini 400 social index?

Launched in 1990, the Domini 400 was the first benchmark index constructed using environmental, social and governance factors.

Life Technologies of Carlsbad -- formerly known as Invitrogen -- is one of three San Diego County publicly-traded companies that are part of the 400 company index. The others are Qualcomm and Gen-Probe.

The whole concept of socially responsible investing continues to gain support. Many investors now have the attitude that they can make profitable choices and still be loyal to their core beliefs. Also, in a growing number of situations, they use their investments to influence corporate decisions.

It's no wonder. Agree or not, there have been a number of situations recently that have angered investors. Everything from the Madoff mess to executive bonuses has rattled confidence and raised questions about the direction many companies are headed.

"The array of fundamental challenges from corporate governance and regulatory oversight to climate change and energy diversification, to name just a few, is daunting," said Bennett Freeman of Calvert Investments, a mutual fund company that specializes in SRI. "Investors must take advantage of this opportunity to engage policymakers to build a much more accountable and sustainable future."

Of equal importance is where these funds don't put their money.

The Domini index clearly says it will not invest in companies involved with tobacco, firearms, alcohol, gambling or nuclear power.

While some investors have no problem owning these companies, SRI types prefer to look elsewhere.

Certainly the headlines seem to be screaming about opportunities in alternative energy such as wind and solar energy. Few companies in this sector have been able to prove that they are financially viable, but investor dollars continue to flow their way in large quantities.

Those of us who have been around a while know that this kind of mania has existed before. Previous energy crises also caused investors to flock to the hot stocks of companies that promised to provide the ultimate technology to make alternative energy an economic reality. Maybe this time it will happen as billions of taxpayer dollars are being thrown into research.

I mention this simply to suggest that caution is appropriate for socially responsible investors as well as all investors.

So, how is SRI working out? It was once perceived that people who invested with their hearts as well as their heads would often have to sacrifice returns. However, that's not the case. When the markets are doing well, SRI stocks follow the overall market.

Since its inception in 1990, the Domini 400 index has average an annual return of 7.25 percent, slightly better than the 6.57 percent average for the S&P 500.

George Chamberlin is a North San Diego County-based financial journalist. Contact him at georgeccsd@yahoo.com.