The purpose of Deborah R. Mayerson was to assess the relative impact of climate, trust, and bureaucratic structure upon teachers' perceptions of organizational effectiveness. An existing data set compiled by Nancy Casella (2006) for her dissertation was analyzed. The data consisted of questionnaire responses of a random sample of 220 public school teachers in the state of New York. Scores were provided for a measure of climate (OCI, Hoy, Smith, and Sweetland, 2001), trust (Omnibus Trust Scale, Hoy and Tschannen-Moran, 2003), enabling bureaucracy (ESS, Hoy and Sweetland, 2001), and teachers' perceptions of school effectiveness (IPOE, Miskel, Fevurly, and Stewart, 1979). The relative contributions of the eight independent variables: Collegial Leadership, Achievement Press, Teacher Professionalism, Institutional Vulnerability, Trust in Principal, Trust in Colleagues, and Trust in Clients to predicting Perceived Organizational Effectiveness was assessed. Simultaneous multiple regression was used to determine which variables made a significant unique contribution. The full regression model was significant (R[superscript 2] Adj.=0.451, p less than 0.001). Only two of the independent variables made significant unique contributions to predicting Perceived Effectiveness, Teacher Professionalism (beta=0.309, p less than 0.001) and Achievement Press (beta=0.264, p less than 0.002). [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/en-US/products/dissertations/individuals.shtml.]