Pennsylvania Association of Nonprofit Organizations (PANO) is the Pennsylvania (PA) statewide membership organization serving and advancing the charitable nonprofit sector through leadership, advocacy, education and other services in order to improve the overall quality of life in Pennsylvania. PANO helps charities become more efficient and effective through collaboration, cooperation and the sharing of resources and information. PANO helps charities succeed together where they can not succeed separately.
Their guide to starting a Not For Profit Organinzation in PA is here
http://www.pano.org/Nonprofit-Resources/Forming-A-Nonprofit/