Firms cooperate not only with complementary partners such as their suppliers and customers, but also increasingly with their competitors which can result in a simultaneous pursuit of cooperation and competition – coopetition (Brandenburger and Nalebuff, 2011). Coopetition is a paradox as it involves firms interacting with two contradictory logics – cooperation and competition, which their contradictory, yet interrelated, demands seem logical in isolation, but absurd and irrational when appearing simultaneously (Peng et al., 2017). The extant research on the role of the competitor as an NPD partner also throws conflicting results; positive and negative NPD performance. This variance could be related to the firm’s internal capability to manage the partnership in NPD activities. This research aims to investigate these issues: Part I examines ‘the paradox of coopetition’ by investigating how firm’s experience of coopetitive relationship influence on firm’s coopetition capability. Part II investigates the key antecedents and outcomes of coopetition capability on the competitor partnership for new product development. The findings suggest a balanced-strong coopetition and alliance management capability are useful to build coopetition capability. In turn, coopetition capability has direct and indirect effects on NPD performances.