Downsizing is big news across the country.

When David A. Duffield sought to build a 72,000-square-foot home on rural Country Oak LaneAlamo, Calif., neighbors like Elizabeth Pelletier took exception. "It has felt like a hostile takeover," she said.

But here in the Bay Area, home to one of every 20 of the nation's billionaires, downsizing has been redefined: a reduction of 54,500 square feet in a mansion planned by David A. Duffield, the billionaire founder of PeopleSoft Inc.

To others on Country Oak Lane, who have taken to Mr. Duffield like the Hatfields to the McCoys, the shrinking of his French Norman-style mega-mansion to 17,500 square feet - from the 72,000 square feet that he had originally planned - and the elimination of a 20-car underground garage are not enough. Over the Thanksgiving weekend, a brigade of 29 members of the Bryan Ranch Homeowners Association went door to door and succeeded in amending the homeowners' covenants. The amendment restricted the size of the private subdivision's houses, including Mr. Duffield's, to 10,000 square feet, max.