Teamwork is the cornerstone of accelerating an organization toward a desired goal smoothly. Modern school administrators should encourage their educational staff to realize the importance of job participation and prepare themselves professionally for the long run. The purposes of this research were to study and compare the roles of teamwork of school administrators under Chanthaburi Primary Educational Service Area Office, classified by working experience and school size. The sample used in this research was a group of 331 school administrators and teachers under Chanthaburi Primary Educational Area Office resulting from Krejcie and Morgan’s comparison table and proportionate stratified random sampling method. The instrument was a questionnaire about the role of teamwork of school administrators under Chanthaburi Primary Educational Area Office. The research instrument for data collection was a five – rating scale questionnaire with a discrimination of between 0.28 and 0.74 and a reliability of 0.94. The data was analyzed by: percentage, mean, standard deviation, t-test and one-way analysis of variance.