Capenet.org  - The Council for American Private Education (CAPE) is a coalition of national organizations and state affiliates serving private elementary and secondary schools. There are 27,000 private schools in America, and more than six million students attend them. CAPE member organizations represent about 80 percent of private school enrollment nationwide.

US Dept. of Education - Education Resource Organizations Directory (EROD) (a division of ED.gov) helps identify organizations that provide information and assistance on a broad range of education-related topics. You can search, for example, by word (try "advocacy") or by state (see these Kansas resources).