Abstract. This study examined the best-fit model of organizational citizenship behavior (OCB) among teachers, focusing on how school culture, quality of work life, and interpersonal support influence it. Using a non-experimental quantitative design, the researchers gathered data from 400 secondary school teachers in Region XII, Philippines, through stratified random sampling. Standardized questionnaires measured OCB and the three influencing factors. Data were analyzed using descriptive statistics, correlation, multiple linear regression, and structural equation modeling (SEM). Results showed that teachers had a very high level of OCB, while school culture, quality of work life, and interpersonal support were rated high. Strong positive relationships were found between each of the three factors and OCB. Among them, the quality of work life and interpersonal support significantly and positively predicted teachers' OCB. The final model (Model 3) was identified as the best-fit model based on SEM criteria, confirming that these two factors are key influences on OCB. The study suggests that improving work-life quality and fostering supportive school relationships can enhance positive teacher behaviors beyond formal roles.

Keywords: Educational management; Interpersonal support; Organizational citizenship behavior; Quality of work life; School culture; Structural equation model; Philippines.