The Philadelphia School Partnership has received a $5 million challenge grant from the Walton Family Foundation to help create and expand high-quality city schools.

It's the largest gift from a national philanthropy the nonprofit partnership has received since its founding in 2010.

"We're thrilled to get a big contribution like this," said Mark Gleason, the partnership's executive director. "What is especially encouraging about it is this makes more than $10 million we've attracted from national foundations to Philadelphia after years and years of [grants] not coming to Philadelphia. This is a sign there's a real opportunity in this city."

He said the money will go into the partnership's Great Schools Fund, which aims to create 35,000 new seats in high-performing city schools - district, charter, or private.

The funds will be provided over three years. Terms call for the partnership to raise a partial match of just over $3 million in local pledges to obtain the full amount, Gleason said.

The Walton Family Foundation, which is based in Bentonville, Ark., was created decades ago by the late Sam and Helen Walton, founders of Wal-Mart Stores Inc. Education is one of the foundation's major areas of interest. It has given more than $1 billion to K-12 education efforts, especially those that expand options for low-income students.

Some public school advocates have criticized foundation for supporting vouchers that use taxpayer money to send children to private schools and have called it anti-union.

Gleason said Walton's partnership grant comes without strings.

"To date, all of our funders have put money in with the understanding that the fund will invest in all types of schools," he said.

Ed Kirby, deputy director of Walton's K-12 education reform area, agreed and praised the partnership's work. He said Gleason's organization and the foundation share the same mission of empowering parents to choose quality schools and strengthening those schools.

He also said Walton's $5 million pledge was not connected in any way to the fiscal crisis in the Philadelphia School District.

"This investment is all about school creation and development," Kirby said in an interview Wednesday. "We're following the ups and downs in Philadelphia of the fiscal crisis and otherwise, but this is independent of all that."

Contact Martha Woodall at 215-854-2789 or martha.woodall@phillynews.com