With growing use of interorganizational systems the scope of interfirm collaboration has increased considerably, particularly in the supply chain context. An important prerequisite of interfirm collaboration is information sharing. Extant research suggests clear advantages of information sharing. The research presented in this paper addresses antecedents of interorganizational information sharing. Based on findings from interorganizational systems adoption and interfirm collaboration research, a structural model is developed and validated by a quantitative survey among Austrian retailers and manufacturers in the fast moving consumer goods sector. The proposed model explains the effect of internal factors (commitment, information policy, and readiness), inter-organizational factors (relationship, trust, power, and trading partners' readiness), and economic factors (perceived benefits and costs) on information sharing behavior. The results show the relevance of internal factors and perceived benefits. The study reveals particularities of information sharing behavior and can help practitioners to understand what motivates their trading partners to share information.