In 1978, James Vivian established the Yale-New Haven Teachers Institute, a collaborative program between Yale faculty and New Haven public schools designed to improve teacher effectiveness. The program stemmed from work Vivian had begun while director of a history education project that promoted faculty partnerships with public school teachers. Vivian's initial collaboration has mushroomed into today's Yale National Initiative (YNI)--a program taking root in cities throughout the country now held up as a model program for a national teacher's professional development movement. This article describes what YNI offers.