This study uses a quantitative approach with a causal research design. The main objective is to determine the effect of job satisfaction, organizational commitment, and coworker support on the Organizational Citizenship Behavior (OCB) of employees at Bina Mitra Insani Yogyakarta. The research population consists of all employees at Bina Mitra Insani. Due to the relatively limited number of employees, a saturated sample technique was used, meaning that all members of the population were included as respondents. Data were collected using a questionnaire with a five-point Likert scale, supplemented by a literature review to support the theoretical basis. The variables in this study included job satisfaction (X1), organizational commitment (X2), coworker support (X3), and OCB (Y). Validity was tested using item-total correlation, while reliability was tested using Cronbach's Alpha. Data analysis was performed using multiple linear regression, with stages of classical assumption testing, F-test for simultaneous effects, and t-test for partial effects