In a new partnership described as “the greatest of leaps,” Martha’s Vineyard Hospital has entered into an agreement for sharing staff and expertise with Massachusetts General Hospital and Brigham and Women’s Hospital.

The agreement means that the hospitals will share doctors, including specialists that the Island hospital does not keep on staff full-time, such as pulmonary physicians and oncologists. In addition, Island medical personnel will go to the Boston hospitals on occasion for training, and vice versa.

Island people will benefit by receiving a better quality of care, officials said.

“What we are announcing today is the opening of a bridge,” said Jonathan Barnett, chairman of the board of trustees, at a reception yesterday at the hospital. “This bridge will connect us to the future, to the health care of the 21st century. Across the bridge will travel people, patients, physicians, nurses, technicians, health care information, diagnostics, electronic medical records, technology, videoconferencing, telemedicine and finally — and the object — is care.”

And, while it is easy to see the advantages to the Island hospital, officials from Mass General said they will benefit too.

Andrew Warshaw, the hospital’s chief of general surgery and a Chilmark homeowner, spoke of the value of the Vineyard hospital as an alternative learning environment to the elite academic world of Mass General, which is an affiliate of Harvard Medical School.

“These are not just words,” he said, introducing a Mass General surgical resident who is working in the Vineyard Hospital and is “the first in what will hopefully be a long line of trainees, who come here to learn what we can’t teach them. It’s something different here. This is a different environment. It’s an important environment. To come down here and see what care is on Martha’s Vineyard is going to be a piece of his education that is unique, and which none of our other residents will have had.”

The alliance has been in the works for several months.

The Vineyard hospital’s new partner is formally known as the Partners HealthCare System — a coalition that includes Mass General and Brigham and Women’s as well as other health care institutions and 850 primary care physicians. The Vineyard’s hospital has long had an informal relationship with the two hospitals.

The partnership does not include any financial link between the organizations.

Still, it is a positive development for the financially troubled Martha’s Vineyard Hospital. Mr. Barnett noted that Massachusetts General Hospital was recently ranked third in the country by U.S. News and World and first in the region.

And from now on, when patients are airlifted to Boston they will automatically go to Mass General or to Brigham and Women’s, unless the patient or the patient’s family requests another destination.

Other of the partnership’s benefits will not be immediately obvious to the public. Still, the increased training opportunities, tightly linked referral network and the sharing of staff will result in better care, officials said.

For those at the reception — including about 25 members of the hospital staff, some in white lab coats — the mood was bright.

“From an employee and a native Islander point of view, this is great,” said Kenny Ivory, a maintenance mechanic and the operator of the hospital’s wastewater treatment plant.

He said that he knows of a few hospital employees who have been a bit nervous about whether they will still be needed at the hospital. But Mr. Ivory, after listening to speakers, said he is enthusiastic about the development.

“I think it’s fantastic,” he said, guessing that most other employees feel the same. “I think they’re happy about it.”

Also at the reception were several Island officials, many of whom seemed to be pleased by the news.

“It’s really the best thing to happen to health care on Martha’s Vineyard in a long time,” said Timothy Carroll, who was there representing the county commission.

On the other hand, Roger Wey, who is an Oak Bluffs selectmen and who served on the selectmen’s hospital task force, mentioned that he remains deeply concerned about the hospital’s finances.

Still, he said that the new allegiance is good news for the Island.

“I applaud Charlie Kinney,” he said, referring to the hospital’s chief executive officer. “This is a very good thing, a very good thing.”