Despite the importance of customer participation in new product development in business-to-business markets, its specific challenges and potential downsides are under-examined. Drawing on the boundary theory perspective, this study integrates conflict into the customer participation literature and proposes that whereas customer participation as the information provider (CPI) mitigates customer-developer conflict, customer participation as the codeveloper (CPC) increases it. Furthermore, the nature of new products moderates such effects. Market newness attenuates the role of CPI in mitigating conflict and reduces the positive effect of CPC on conflict; by contrast, technology newness increases the influence of CPC on conflict. The empirical results from a sample of 181 high-tech firms in China largely support these propositions, which offer important implications for customer participation research and practices.