"Wealthy families lie at the very center of the American experiment," Gregory Curtis writes in his book, "Creative Capital." "Private capital is an essential, even a definitive aspect of the American version of democratic capitalism."

If you don't pledge allegiance to that statement, chances are your fortune is not ample enough to be managed by Mr. Curtis and Greycourt & Co.

The Shadyside firm advises about 100 clients, most of them wealthy families who entrust an average of about $160 million to Greycourt. About 25 percent of the nearly $10 billion Greycourt is entrusted with comes from foundations and other nonprofit organization. The firm's minimum annual fee is $100,000.

"Our real market starts at about the $25 million level," said Mr. Curtis, who cut his teeth serving as the principal financial adviser to Cordelia S. May, a Mellon family heir and sister of financier Richard M. Scaife.

Greycourt employs about 50 and also has offices in Charlotte, N.C.; Houston; and Portland, Ore.

Mr. Curtis, the chairman, had a broader market in mind when he founded the firm in 1995. Back then, he hoped to deliver financial advice over the Internet to families of more modest means, charging fees ranging from $500 to $3,000. But he underestimated two things: the scale needed to make the business model profitable and the quality of financial advice wealthy families were receiving.

"We had over 300 clients at the time, but you really needed thousands," he said. "We couldn't make any money on the small [families], so we refocused on the big ones."

Wealthy families typically relied on bank trust departments, which may or may not have been familiar with their clients' needs or how investments affected the family's tax bill or estate plans. In most cases, the bank sold its own products to the clients, a conflict of interest since the bank's offerings usually weren't the best the market had to offer, Mr. Curtis says.

Greycourt responded with what he refers to as "open architecture." The firm finds the most suitable investments available and gets paid by its clients for making the recommendations and monitoring the performance of their portfolio.

"Our job is sort of to be supershoppers," he said.

Mr. Curtis' ambition was to be an English teacher when he was writing poetry and attending Dartmouth College. However, he ended up at Harvard Law School, then signed on at Reed Smith in 1973 and went to work for Ms. May in 1979.

But Mr. Curtis never completely surrendered his literary ambitions. He regularly writes thoughtful, footnote-studded papers Greycourt uses to market its services to the 200,000 or so U.S. families that make up its target market.

"You can't advertise to this client base. It doesn't mean anything to them," Mr. Curtis said. "It's a word-of-mouth business."

His seminal work is "Creative Capital," a 400-page tome Mr. Curtis says "is a tangible demonstration to people that we know what we're talking about." His theme is that building, managing and deploying wealth "are activities that lie at the very soul of what has made America great." Quoting everyone from Voltaire to G.K. Chesterton to P.G. Wodehouse to make his point, Mr. Curtis argues that since wealth is so important to America's success, wealthy Americans have a civic obligation to be responsible stewards of their fortunes and put them to work for the good of their country.

"Most families blow through their money in three generations. Part of our job is to see that doesn't happen," he said.