If you're one of Chris Bidwell's competitors, be afraid—be very afraid.

The veteran Smith Barney advisor has designed a total of 55 retirement plans for small-business owners and their employees so far. Sure, margins may be thin and the work painstakingly detailed, but that doesn't bother Bidwell. That, in his view, is simply the price a savvy financial planner pays in order to capture the big prize: the mandate to handle the business owner's personal assets and those of the grateful employees as well. "If you are a competitor of mine, and you are managing the personal assets of a small-business owner but think dealing with setting up their 401(k) is going to be too cumbersome, then watch out—I'm going to handle the retirement business and I'm now looking to take over that personal account from you as well," the Dayton, Ohio–based planner warns rivals. "If you look beyond the trees and into the forest, there are so many great opportunities in working with small businesses."

Across the country, a growing number of financial advisors like Bidwell are recognizing the potential opportunities that lie in serving smaller businesses. These companies are the engine of U.S. economic growth, with millions of firms launched each year and collectively accounting for a large chunk of the country's gross domestic product and employment creation. But traditionally, their owners rarely became consumers of financial planning services until their businesses had grown very large, gone public or been sold, leaving the entrepreneur with an unprecedented sum of cash and a need for guidance on how to manage the windfall.

These days, however, small-business owners find they need assistance from planners at every stage along the way to that goal, whether it's helping them knit together a network of tax, legal and accounting experts, setting up retirement plans to retain and attract top talent or—ultimately—setting up and financing exit strategies. Meanwhile, advisors themselves are recognizing that forging rock-solid relationships with potential small-business clients is easier to do at an early stage in the entrepreneurial life cycle.

"That's when business owners need the most help, and that's when you earn their gratitude and loyalty," says Heather Hutchinson, founder of Hutchinson & Ziegler Financial Advisors, a San Rafael, Calif.–based planner with $25 million in assets under management. "By the time they have accumulated enough wealth to be attractive to most planners, they don't face some of the tough issues anymore." About half of her clients are small-business owners, and she saw the challenges that they all confront firsthand when her husband ran his own small firm. "I realized that this market can use the kinds of services planners can offer, and that relatively few people seemed to be jumping on that opportunity," she says. "It requires effort—you have to be prepared to network, to build relationships with all kinds of service providers, to listen and to recognize and work around the fact that small-business owners have very particular needs."

Heather Hutchinson, founder of Hutchinson & Ziegler Financial Advisors, says many business owners sign on when they need to extract funds from the business.

It's Not Just Business—It's Personal

That starts with the fact that their business and personal finances tend to be inextricably linked, as are their personal and professional identities. A planner who works with a small- business owner on the latter's personal portfolio is likely to quickly discover that a suggestion that they extract more cash from the business to invest in some kind of qualified retirement plan is often greeted with surprise or even exasperation. "Most small-business owners have reinvested all their excess cash in the business because it has been more profitable than any other investment and because they feel they have some control over the risk," says Mark Stein, a fee-based planner and president of Aegis Financial Group, a Phoenix-based firm. "I often hear them argue, 'Hey, instead of putting my money into a mutual fund, I can buy two or three more trucks and expand my business.'" At the other end of the spectrum is the exhausted entrepreneur who, after spending decades building a company, now wants nothing so much as to find a way to untangle his own finances and recoup the benefit of his labor in the form of cold, hard cash. At no stage can the advisor assume that he or she can treat personal finances in isolation from the business.