Pfizer Inc. has named Atrium Staffing of New York City as a primary provider for payrolling services involving independent contractors and contingent labor throughout the company's operations in the United States and Puerto Rico.

Atrium already performs much of the pharmaceutical giant's payrolling of independent contractors in Connecticut, but the new agreement with Pfizer will expand its opportunities, said Atrium's president and chief executive Rebecca Cenni. She added that Atrium is looking for office space in Groton and New London and plans to expand into the Connecticut market with an initial staff of two or three.

"We can ramp up maybe beyond that, but it depends on the economic climate," she said. "We're very excited to be able to contribute to the economic vitality of the state."

Pfizer has hundreds of contractors who work at its research-and-development campuses in Groton and New London.

Pfizer said it didn't expect the contract with Atrium, awarded on the basis of a competitive bid, to have an effect on temporary-staffing firms such as Execupharm, Johnson Controls, Satyam, Infosys and others it regularly uses.

Cenni would not give specific details about Atrium's contract with Pfizer, but said the company traditionally has provided administrative and clerical services on both a full-time and part-time basis. Atrium, whose relationship with Pfizer goes back to its beginnings 15 years ago, helps companies of all different sizes with their employment and payrolling needs, she said.

"Basically, Atrium will provide the evaluation of independent contractors to ensure compliance in hiring, and they also provide the payrolling process for these independent contractors," said Pfizer spokeswoman Joan Campion in an e-mail. "It will also continue to provide clerical and administrative work."

Atrium, a certified Woman Business Enterprise, said it would act as the employer of record for independent contractors and workers doing short-term projects for Pfizer. For instance, summer interns, American information-technology personnel working on short-term projects and retirees coming back to work at Pfizer would go through Atrium, the company said.

Atrium works closely with MBO Partners of Herndon, Va., in the vetting of prospective independent contractors, including those at Pfizer.

Atrium will be responsible for consultants and contractors who deal closely with Pfizer in such areas as information technology, science and administrative services. It does not serve outside contractors that employ people in such areas as janitorial or food services.