Behavioral commitment levels of group members were examined under conflict of interests between individual and collective tasks in a work-group scenario. Commitment was conceptualized as the amount of time and effort resources that individuals chose to allocate to the group task. Seventeen groups of three allocated 100 time and effort resource units to individual and group tasks for each of four trials. The level of commitment to group work increased, partially because over-rewarded persons increased group contributions more than underrewarded persons decreased them. However, the variance of allocations to the group task did not decrease over trials. Potential implications of the findings for organizational research and practice concerning work groups are discussed in terms of the roles of equity, comparative referent use, and information exchange.