One morning last week, a tired-looking businessman named Richard Du was pacing around the partly renovated space that would soon house Dumann Realty, his commercial real estate brokerage.

“We’re moving in this Friday,” Mr. Du said with conviction, despite the missing ceiling tiles, the wooden planks leaning against the walls and the whine of the power saw. He glanced over at Roberta Wood, a representative of the building’s owners, who was standing nearby. “She’s a lovely landlord,” Mr. Du said. “So far.”

But Ms. Wood is not just any landlord. She is a project manager for Advance Realty, a corporation affiliated with the Communist Party USA. And the building with the elegantly ridged facade at 235 West 23rd Street, near Eighth Avenue, where Mr. Du has just signed a 10-year lease, has been the party’s headquarters since 1977.

For just over a year, the party has gradually been withdrawing from four of the building’s eight floors. The freed space is being rented out — to Mr. Du, to a record label, to an art supply store and to various other capitalists. Leases have been signed for all but one of the rentable floors.

“They weren’t being utilized,” explained Ms. Wood, a former electrical worker who is the labor editor of the People’s Weekly World, the party’s newspaper. “We were just kind of spread out.”

The Communists of West 23rd Street do not see a problem in renting out their property for cash. “We live in a capitalist system,” said Libero Della Piana, the party’s bearded, bushy-haired communications director. “We know that in order to function, you have to get by in the system. We’re not going to change the world by not charging rent for our space.”

The move has entailed sacrifices. Although some of the party’s files were put into storage, most were given to the Tamiment Library at New York University, which announced last week that the party had donated 12,000 cartons of its records. The newspaper’s editorial staff had to decamp to Chicago.

Other offices, including those occupied by the Young Communist League and the party’s book publishing arm, have moved to a cramped warren of rooms on the building’s seventh floor, where Sam Webb, the party’s national chairman, shares space with one of the newspaper’s proofreaders.

And how does Mr. Du feel about renting from avowed enemies of capital? “I come from Vietnam myself,” he said, grinning. “It’s the best party ever, in my book.”