If you're looking for companies that combine economic gain with attention to environmental and social developments, then the concept of corporate sustainability can point you in the right direction. Recently, a leading index of sustainability-focused companies made some changes that you'll want to pay attention to.

First, the good news: 33 companies were added to the Dow Jones Sustainability World Index. These include Johnson & Johnson (NYSE:JNJ), Coca-Cola (NYSE:KO), and Colgate-Palmolive (NYSE:CL). They were rated highly for good corporate governance practices, risk and crisis management, environmental reporting, labor practices, human capital development, corporate citizenship, climate change mitigation, branding, and more. So ... yay for them!

Now the bad news: 33 companies were removed from the index. These include National Grid (NYSE:NGG), Advanced Micro Devices (NYSE:AMD), and Waste Management (NYSE:WM). It's easy to assume that they fell off the list because of a slackening in their dedication to sustainability.

But hold those horses. There may be a different explanation. The companies added may just have been more impressive. With each passing year, there seems to be more attention paid to corporate responsibility. Wal-Mart (NYSE:WMT), for example, has been embracing organic foods. Coca-Cola has added hundreds of hybrid trucks to its fleet, has invested in solar and wind power, and has improved the energy efficiency of its coolers and warehouse lighting, among other things.

Sustaining your portfolio
With more companies becoming better citizens, does it make sense to look for investments among these companies? I have mixed feelings. Over the past five years, the Dow Jones Sustainability World Index has outperformed the broader Dow Jones Global Large-Cap Total Stock Market index by about 1.5 percentage points annually. Since its inception in 1999, though, its 8% average annual gain trails the broader index's 11.7% average return.

If you're interested in investing in the most responsible companies, your best bet might be to simply take note of which companies receive high marks for sustainability and then choose from among those.

One place to do further research is our Motley Fool CAPS community. Below you can check out the star ratings for the companies mentioned in this article. (Remember that even the companies dropped are worth considering, as they had made the list before and surely have various ongoing initiatives you might look into.)

Company

CAPS Rating
(out of five)

National Grid

*****

Waste Management

*****

Johnson & Johnson

*****

Coca-Cola

****

Colgate-Palmolive

****

Wal-Mart

***

Advanced Micro Devices

**

Data: Motley Fool CAPS.

There is a way to mix your convictions with your investing. By tracking how big companies do not just financially but ethically, you can make sure your money's working for you in more ways than one.

If you're interested in socially responsible investing, exchange-traded funds can make it easy. Follow the link to an article from Selena that will give you a good introduction.

Longtime Fool contributor Selena Maranjian owns shares of Johnson & Johnson, Wal-Mart, and Coca-Cola. Coca-Cola and Wal-Mart are Motley Fool Inside Value recommendations. Johnson & Johnson, Coca-Cola, and National Grid are Motley Fool Income Investor recommendations. Try any of our investing newsletters free for 30 days. The Motley Fool is Fools writing for Fools.