This study investigated organizational citizenship behaviours (OCBs) in a sample of 154 school teachers from Victoria, Australia, of whom 101 were in permanent employment and 53 on fixed-term contracts. Participants completed measures of OCBs, job insecurity, organizational commitment, organizational identification, job satisfaction and work values relating to influence, variety and skill utilization. Results showed that the contract teachers reported more job insecurity and more OCBs compared to the permanent teachers. OCBs were positively related to perceived job insecurity and negatively related to opportunities to satisfy influence and skillutilization work values for the contract teachers, and positively related to organizational commitment, organizational identification and to opportunities to satisfy variety and skill-utilization work values for the permanent teachers. Results were discussed in relation to the different functions that OCBs were assumed to serve for both groups of teachers and the possibility of conceptualizing OCBs using a motivational analysis that takes account of expectations and goal structures.