The Washington Post Co. said Monday that it has agreed to acquire a majority stake in Celtic Healthcare, a provider of skilled home health-care and hospice services in the Northeastern and Mid-Atlantic regions.

The purchase price was not disclosed, but Donald E. Graham, chief executive of The Washington Post Co., said in a statement that the acquisition is “part of the Post Company’s ongoing strategy of investing in companies with demonstrated earnings potential and strong management teams attracted to our long-term investment horizon.”

Founded in 1996 in Mars, Pa., by Arnie Burchianti, a physical therapist, Celtic Healthcare has $43 million in annual revenue and serves about 2,000 patients from nine locations spanning western, central and northeastern Pennsylvania and Montgomery and Baltimore counties in Maryland. Celtic Healthcare employs proprietary technology and specialized chronic-disease management programs.

Burchianti will continue to run the business as chief executive and co-owner, The Post Co. announced. The Post will provide capital for expansion.

Celtic Healthcare relies heavily on funds from Medicare, which provides hospice benefits “for extended periods of time based on the assessment of the patient,” according to Celtic’s Web site. In its blog last November and again last month, the company posted appeals from health industry groups asking people to lobby Congress to defeat Medicare funding cuts and increases in co-pays.

Jodi McKinney, director of corporate communications at Celtic, said the company hopes to tap The Post Co.’s “financial resources and long-term commitment” to expand and “eventually serve tens of thousands of patients with care in their homes.” She noted that Medicare is planning to penalize hospitals for readmitting patients for the same illness, which she said should boost the need for good home care.

The Post Co.’s foray into health care takes the company in a new direction. In addition to its flagship newspaper, the company owns Kaplan education businesses, a cable unit and half a dozen local broadcast television stations.

In his statement, Graham said, “We are a diverse group of businesses sharing common goals and values but each with its own identity and workplace culture, and with management responsible for its operations.”