I just decide what's important to me and choose companies that match my philosophy. I had looked into socially responsible mutual funds, but some of the companies they invested in didn't match my values. I look for companies that are good to their employees and to the environment, that are making an effort (documented, not just their say-so) to use renewable energy, whose CEOs aren't making outrageous salaries while paying their employees poor wages, who don't 'outsource' at the expense of American workers, etc. There are other things, but the important thing is each person has to decide for herself which values are important, and then research the companies that match. There are several decent 'green investing' sites where you can find the information. If you type in either 'green investing' or 'socially responsible companies' or some variation thereof, you will find lots of information.