Why is it still difficult to use investing as a tool to make a positive impact on society? Lots of investment professionals, including large Wall Street banks, are getting involved in "impact investing" (the term is said to have emerged only as recently as 2007), because their clients are asking them to. But it's not easy to do; an impact investment must "make a difference," and not only to the coffers of the investor. Such win-win investments are often small, and are hard to come by.

Unlike "ESG investing," which adds environmental, social and governance aspects to the financial analysis of a company, impact investing must bring actual social or environmental returns along with the financial. An ESG investment is an investment in a portfolio of companies that have been screened for certain criteria, such as a fossil free portfolio, or an index of companies that seek to improve their environmental and social performance year after year by embracing ESG as a business strategy.

An impact investment goes a step further: it must offer to reduce homelessness, or break a pattern of criminal behavior, for example. Investments should be made in "net positive " companies or projects, where the pluses of social or environmental impact outweigh the minuses.

Impact investing is certainly doable, and is accelerating. In its seventh annual survey, published in May 2017, the Global Impact Investing Network, or GIIN, reported on data from 209 respondents managing $ 114 billion in impact investing assets. These included for-profit fund managers, foundations, family offices, pension funds and other types of investors. In 2016, respondents said they collectively invested $22 billion into almost 8,000 deals. They also said that they plan to increase the volume of invested capital by 17% in 2017. Those that had completed the survey last year as well said their capital invested had increased 15% in 2016 over 2015.

Crowdfunding is one tool, only recently unleashed in the US investment scene, that is certain to have an impact. In May 2016, Title 3 of the JOBS Act made equity crowdfunding legal. There are 29 funding portals now registered with the SEC, where entrepreneurs can attract capital. Some of them include impact investing as a focus.

But small investors shouldn't rush to put their retirement savings into a project they don't have the skills or resources to vet. The emergence of experts qualified to find and vet high-impact projects with good financial returns is the trend to watch in the coming months and years.

An example of what we can expect for the future is a new website called ImpactUs. Its vision:

· "Make the impact investing market accessible to all;

· Connect mission-driven organizations to investors through collaboration and shared infrastructure that reduces overhead; and

· Create best-in-class experiences for impact investors."

ImpactUs, which is registered not as a funding portal but as a broker dealer, launched in April featuring four issuers that had been vetted on behalf of potential investors. The issuers chose to be available on the ImpactUs website and went through a similar financial due diligence to those required by most brokerage firms, as well as a review of their intent to make a societal difference. Though ImpactUS doesn't make recommendations, through its new online platform, investors and advisors can connect directly, and invest in Iroquois Valley Farms if they are interested in restorative farmland finance, Shared Interest if they'd like to help entrepreneurs in low-income communities in Africa, Envest Microfinance, for universal access to financial services, or CommonBond Communities, an affordable housing provider in the midwest. In these early days, the investments featured are only available to accredited investors.

The idea that this sort of platform can be brought to scale reminds me of how Kiva democratized micro lending. It's a pretty exciting prospect.

A quick note on financial performance of impact portfolios: the 2017 GIIN survey says an overwhelming 91% of respondents reported that their investments either met (76%) or outperformed (15%) their expectations for financial performance, while meeting (79%) or exceeding (20%) their expectations for impact performance.

The fact that societal impact can go hand in hand with financial returns is wonderful. But what is even more appealing about the impact investing approach is that it can begin to shift the way we think about problems, looking at whole systems to find solutions. What are the problems that created homelessness in the first place? How can we make farms restorative, and more financially viable over the long term?

According to the GIIN survey, more than a quarter of respondents were already tracking the results of their investments within the framework of the UN Sustainable Development Goals only a year after the goals were introduced, and another third said they planned to start doing so. If everyone were to frame their investment choices around such goals as eliminating poverty, preserving ocean ecosystems and fostering innovation for sustainable cities, the world would certainly begin to look different.