When River Associates Investments LLC began to fundraise a couple years back, longevity became a big selling point.

"We've been doing this a long time," says Mark Jones, a partner with the Chattanooga, Tenn.-based firm, which opened its doors 23 years ago this month. "I can't tell you how many institutional LPs told us, 'The fact that you have a six in your fund's name is impressive.' "

After all, the world of lower-middle-market private equity is populated by hundreds of firms that come and go. They raise -- if they're lucky -- one fund and then disappear into the financial ether. Fundraising has become considerably more difficult since the 2008 financial crisis, and the small funds are especially vulnerable.

River Associates closed its River VI in May. It garnered $222 million in commitments, topping its $200 million target and doubling the size of River V. For the first time, the firm attracted institutional capital, adding 10 new limited partners while retaining 18 of 20 previous investors.

With a flag still firmly planted in basic industries buyouts and retention of top management, River Associates offers consistency as well in its choice of investments. Earlier this year, it acquired out of Fund VI Industrial Magnetics Inc., a Missouri company that, as the name implies, makes custom industrial magnets, and Auto Air Export Inc., a Texas concern that manufactures air conditioners for the automotive aftermarket.

The firm wouldn't detail investment amounts. Jones, however, says that both purchases fit squarely into River Associates' acquisition matrix: equity between $10 million and $30 million in companies with Ebitda between $3 million and $10 million.

"We don't really chase many larger transactions," comments Jones, who believes that higher Ebitda translates into more competition and higher purchase price multiples.

The current fund, Jones says, will allow River Associates to acquire these kinds of companies and also underwrite add-on acquisitions, without having to worry about quickly bumping into an unhealthy portfolio concentration level.

While the firm has invested in companies spread across 20 U.S. states and two Canadian provinces, it illustrates a kind of heartland approach to private equity that seems to characterize many of the successful lower-middle-market shops. It boasts a degree of predictability that, boosters maintain, serves everyone well, investors as well as acquisition targets.

"It's very, very rare to find a group like River," says J. Lyons Brewer, who heads Atlanta-based placement agency LB Group LLC. "They have a solid track record, a solid partnership that hasn't strayed. It's a consistent culture on the business side of the firm as well as the financing side," says Brewer, who collaborated with River Associates on its most recent fund. "Everyone is pulling in the same direction."

Of course, fundraising is never a sure bet, and institutional investors can be especially tough-minded when it comes to smaller funds. Even with a history that stretches back two decades, River Associates navigated uncertain waters when it targeted institutional investors. The firm had relied on family offices for past LP support and knew that, in order to broaden, it would have to overcome a dilemma smaller funds face with larger institutions and their placement agents. Call it the "too small, too big" rule: Institutions don't like writing checks for less than $50 million, but won't commit to more than 10% of any one fund.

"It's a very competitive market to raise capital," says Jones, who stresses the importance of being able to "effectively and simply articulate differentiation from other GPs out there" in the lower middle market. "What [institutional investors] are most interested in: Is it a fair assumption, after substantial due diligence, that track record is going to be repeatable going forward? They're looking for consistency, consistency of people, consistency of returns, consistency of investment thesis."

However, "you'd be surprised," he continues. "There are a number of institutions out there that will write smaller checks with the hope that they can grow with you. If you do your job, they can put more money into future funds."

According to Brewer, River Associates overcame hurdles with relative ease. Neither he nor the firm would reveal the names of limited partners, but they are described as a mix of insurance companies, university endowments, funds-of-funds and a pension fund asset manager.

The firm's story was helped when River Associates pulled off its largest-ever exit in the middle of fundraising. In May 2011, River Associates sold its controlling interest in Coining Holding Co., which makes elements called solder and brazing preforms, used in semiconductor packaging. Nothing terribly glamorous, except the $148 million sale to publicly traded Ametek Inc. represented a gross internal rate of return of 76% and a more than 6 times return.