Twenty homeowners in Arlington's Courtlands area, taking a cue from nearby residents, have united to sell their properties in a single package to capitalize on the multimillion-dollar, high-rise development boom around the county courthouse.

The 20 are the latest group in the county to band together to maximize their profits, following by six months a group of 22 Courtlands homeowners who are selling to a different developer for an estimated $10 million, more than twice the total assessment on their properties. A group near Ballston hopes to do the same.

The new group of Courtlands residents owns land bordered by North Wayne, North Veitch and North 14th streets and the Quality Inn, adjacent to the planned $150 million Court House Plaza project and a $125 million residential project.

The 20 were originally part of the first Courtlands group to try to sell their property, but they broke with their neighbors, saying they believed they could get more for their 5.2 acres than the $37 a square foot the first group is receiving.

Few homeowners were willing to talk about the project yesterday, but Erwin G. Adelberger, who has lived at 1317 N. Wayne St. for 44 years, said he was eager to sell because of rising property assessments brought on by redevelopment. "They're driving us out of here, the county," he said. "The earlier I get out of here, the better."

The owners apparently will get about $60 a square foot if the sales are concluded as expected with Robert M. Stein, president of the Alexandria-based RMS and Associates development firm. He said yesterday he plans to buy the property for about $14 million.

Stein said yesterday that he plans to build a $150 million mixed-use project on the site, which county planning chief Gary Kirkbride said is zoned only for high-rise residential buildings or hotels up to 18 stories, with some retail permitted.

Stein said he would prefer to include an office building, and he is talking to the county about purchasing an acre or more of county-owned land next to the courthouse. The county's Holmes Office Building is there, and the county's shelter for homeless men is on an adjacent parcel. Stein said his project is not dependent upon the office building or the county land.

Many of the houses in the neighborhood are assessed at only $100, but the land is assessed at $250,000 and more. The lots vary from 6,500 square feet to about 25,000 square feet.

The homeowners are being represented by Robert F. Sheridan of Merrill Lynch Realty, who said, "It wasn't easy to assemble that land package. That's a diverse group." Sheridan and Stein said that, following county approval of the project, construction could begin in late fall