As part of a nationwide program to help the homeless, the Harvard Cooperative Society has combined an advertising promotion with a gesture to the community.

Through next Saturday, The Coop will offer customers who bring in old coats substantial discounts on new London Fog jackets. In return, The Coop will deliver the old jackets to the Pine Street Inn, a Boston shelter that serves more than 1000 homeless each day.

The Coop's promotion is part of a program sponsored by London Fog and the National Alliance To End Homelessness, a Washington-based organization of homeless shelters across the country. London Fog initiated the project by supplying the Alliance with its client list.

"Combining advertisement with community service is a great way to do a trade-in," said Kathy M. Little, advertising supervisor for London Fog. "Stores can touch needy members of their own community while helping their business at the same time."

Charles Tieuli, Coop promotions director, said that it was important for stores such as the Coop to help their communities.

"We take the loss on this trade-in, paying for the difference on the coats," Tieuli said. "It's an act of goodwill that we hope will benefit the homeless."

More than 100 stores around the country have been paired with local homeless shelters, according to Valerie S. Hennessey, membership services coordinator of the Alliance. Hennessey said that she arranged the pairs by contacting Alliance shelters located near the stores on the list from London Fog.

Linda M. Wood, the Pine Street Inn fundraising coordinator, said she is particularly appreciative of the coats from the Coop because the shelter will be able to distribute them early in the winter.

"We will have many coats on hand before it gets real cold," she said. "Such donations usually don't arrive until it's already cold outside."

Tieuli said that customers had donated 12 garments since the promotion began on Monday.