By conceptualizing customers' organizational citizenship behavior as a communication cue, a customer evaluation criterion, and a sales performance facilitator in a relational selling context, the authors empirically demonstrate the effect of salespeople's perceptions of their customers' voluntary, prosocial behavior on three components of sales performance. The authors first hypothesize and confirm that salespeople can perceive their customers to exhibit organizational citizenship behavior, and that this important customer cue can serve as a customer evaluation criterion. The authors then demonstrate how salespeople can respond to their perceptions of customers' organizational citizenship behavior in performance-enhancing ways. Results from a sample of 628 business-to-business salespeople suggest that customer-involved sales performance fully mediates the relationship between customers' organizational citizenship behavior and salesperson behavioral performance, and that salesperson behavioral performance partially mediates the relationship between customer-involved sales performance and salesperson outcome productivity. These findings highlight the important role customer-involved sales performance plays as an antecedent to a salesperson's individual performance. Support for the notion that salespeople's perceptions and interpretations of their customers' organizational citizenship behavior can facilitate personal selling and augment sales performance has implications for sales training, salesperson evaluation, and customer evaluation. The authors discuss these and other implications for B2B researchers and practitioners. (C) 2015 Elsevier Inc. All rights reserved.