After a 12-year stint as president of the National Parks Conservation Association, Tom Kiernan has announced his resignation and plans to head a charity in New Hampshire.

Mr. Kiernan will make the move this summer. His new job will be with the New Hampshire Charitable Foundation, which is headquartered in Concord, N.H. This state-wide foundation provides $34 million a year in grants to help support and guide the civic agenda in the state.

“NPCA is an extraordinary organization that I have had the privilege to lead for the last 12 years,” Mr. Kiernan said in a prepared statement. “From helping to ensure that the National Park Service has strong management policies to increasing funding for our national parks and monuments to convening the National Parks Second Century Commission, NPCA has had and will continue to have long-lasting successes in protecting and enhancing America’s national parks for present and future generations.”

It's expected that Mr. Kiernan will remain with NPCA until the middle of June to ensure a smooth transition of leadership.

NPCA’s Board of Trustees is forming a search committee and will be hiring a national search firm to assist in the selection process for a successor.

“While the board is deeply saddened to lose Tom after 12 great years leading NPCA, we fully understand and respect his desire to return to a place that is important to him and his family and to take on a new set of challenges,” said Alan Lacy, chairman of NPCA’s Board of Trustees.

During Mr. Kiernan's tenure, NPCA has seen its field and regional offices increase in number from seven to 24, the number of staff from 65 to 165, and the size of the annual budgets from $17 million to $33 million.