Successful product innovation has increasingly been recognized as an outcome of integrating customers in the new product development process. Despite the attention of this research subject, the comprehension of how to learn from customers is still limited in scope and in depth. This research investigates ‘learning' in the customer integration context and discusses a conceptual framework from learning theory with customer know-how acquisition, dissemination and utilization as critical steps. The paper reports a comparative case study of new product development projects in a business-to-business context. The findings show empirical support for the developed framework and demonstrate the importance of a differentiated consideration of the three steps. They lead to determinants for successful customer know-how integration in new product development projects.