A literature review indicated no studies on the constructs of school organizational climate, teacher demographics, and organizational citizenship behavior in St. Lucia. This study investigated the possible nature of school organizational climate dimensions and demographics on teachers' organizational citizenship behavior in St. Lucia. To achieve this aim, the researcher used a sample of 105 schoolteachers (K-12) during the academic year of 2021. The researcher used the quantitative correlational research design and questionnaires from the literature to gather data through the convenient sampling technique and multiple regression analysis to analyze the data. The results of the regression analysis show that four (4) predictor variables (one of the school organizational climate dimensions and three of the demographics) in the model, individually, had a statistically significant predictive relationship with organizational citizen behavior with a p-value < 0.05. Since the p-value was less than alpha 0.05 (p < 0.05), the null hypothesis was rejected for these four predictor variables, and the alternative hypothesis was accepted. Therefore, the four (4) predictor variables predicted teachers' organizational citizenship behavior (K-12) in St. Lucia. The remaining five variables (two schools' organizational climate and three demographic variables) were not statistically significant. One variable of school organizational climate was excluded from the model because it did not meet the accepted VIF threshold in the research literature. Conclusions were discussed, and recommendations were offered. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]