The major function of a non-profit president is to oversee the entire operation of the non-profit. In most ways, the duties of a non-profit president are no different than those of a president at a for-profit company.
Liaison to the Board

The board of directors ultimately makes decisions for a non-profit organization. It is the president's responsibility to act as liaison between the board and her non-profit's staff.
Fundraising

Fundraising is integral to the operation of most non-profits. It is usually the president's duty to not only oversee the fundraising or development department of a non-profit, but to take an active role in attracting funds.
Finances

A non-profit president is responsible for allocating the organization's financial resources and finalizing budgets for board approval.
Program Development

Non-profits often have program staff responsible for devising and implementing programs. The president oversees this process suggesting new avenues and tweaking existing services.
Evaluation and Strategic Planning

Increasingly, non-profits are being asked to run more like for-profit businesses. Therefore, non-profit presidents are constantly evaluating programs for effectiveness and putting forward long-term strategic growth and sustainability plans.