Why bother trying to understand socially responsible or sustainable investing concepts if you are a mainstream financial advisor? You might not realize it, but you owe it to your clients.

You may have written off these concepts as coming from a bunch of do-gooders who don't care too much about making money. And while some clients might put their personal values ahead of how much money they make, you know that many others-maybe even most-won't sacrifice returns to help the world. And why should they if they don't want to? But if they could make more money by investing in companies that take a lead in environmental or social issues, now that would be another story.

And answering that question-Is it possible to make more money by doing good?-is one of the dramatic shifts in focus that has been going on in the world I will call "investing to make a difference" over the last several years. Clients interested in maximizing returns certainly would want their investment advisors to be familiar with this landscape-it certainly isn't a simple one to traverse for average investors and it's continuing to shift and transform. For starters, we're hearing the term "sustainable investing" used more frequently, but is it the same thing as "socially responsible investing" or "green investing"? Is "socially responsible investing" one specific discipline or an umbrella for a variety of investment styles?

Proponents of sustainable investing draw significant distinctions between its principles and those of traditional socially responsible investing. Basically, they say that traditional SRI is about selecting investments according to personal values without being too concerned about returns, while sustainable investing means looking for companies that have good environmental, social and governance practices because they are better managed and therefore will produce higher profits over the long run. A handful of books have been published on the topic (search "sustainable investing" on Amazon and you'll come up with 24 hits versus more than 800 for "socially responsible investing"), but I think we're going to see a lot more on the topic being published this year.

Two recently published books that provide compelling arguments for sustainable investing are Investing In A Sustainable World: Why Green Is the New Color Of Money On Wall Street by Matthew J. Kiernan and Sustainable Investing: The Art Of Long-Term Performance, edited by Cary Krosinsky and Nick Robins.

Kiernan is founder and chief executive of Innovest Strategic Value Advisors, one of the world's leading sustainability investment research firms. Krosinsky is vice president, North America of Trucost Plc, which uses its extensive database to help portfolio managers understand their carbon footprints, and Robins is head of HSBC Climate Change Centre of Excellence, the goal of which is to evaluate the implications of climate change for the HSBC Group, its global research division and other business units.

After reading one or both, I think that you'll embrace at least some of the thinking on sustainable investing. You'll probably realize, too, that many things will need to happen before environmental and social criteria are considered in mainstream financial analysis.

Meanwhile, don't shortchange your clients by not being familiar with what's happening.