Although some school improvement literature has suggested that schools will improve when unions are removed from the school system, unions have rarely been isolated in the research. This study involved a mixed method case study approach to explore whether support of the local teacher union affected perceptions of school climate, as measured by the Organizational Health Inventory. The study found that teachers who supported the union had more positive perceptions on several of the organizational climate dimensions than teachers who were not supportive of the union. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]