Proactive postsales service (PPS) refers to a supplier taking the initiative to contact a customer to provide service after a sale is complete. It is argued that PIPS leads to faster delivery of service to a broader cross-section of customers than customer-initiated postsales service, or reactive postsales service. The authors argue that mental frames of customers and suppliers engaged in PIPS are more positive and open than mental frames of those engaged in customer-initiated service. On the basis of nine focus groups with 94 managers in both business-to-business and business-to-consumer settings, the authors propose three main dimensions of PIPS: (1) proactive prevention, (2) proactive education, and (3) proactive feedback seeking. They argue that PIPS leads not only to favorable customer-level outcomes (e.g., customer satisfaction) but also to favorable supplier-level outcomes (e.g., greater innovativeness, new product success rate). The authors propose that the value of PIPS varies depending on the product's life-cycle stage, its transaction extensiveness, and network externality. In addition, the value of PIPS varies depending on a customer's usage intensity, openness to experience, and market mavenism. Some key challenges with PPS pertain to implementation issues, such as privacy intrusion, expectation escalation, user identification, and contact routinization. If neglected, these can result in PIPS leading to negative rather than positive outcomes. The authors develop guidelines for addressing these challenges and implementing PPS effectively in both business-to-business and business-to-consumer contexts.