The relationship between cooperation with competitors and product innovation performance was investigated along with the moderating effect of the innovating firm's technological capability and its alliances with universities. The hypothesis that cooperation with competitors has an inverted U-shaped relationship with product innovation performance was tested using data on new product introductions from 1499 Chinese firms. The results support the existence of a bell-shaped relationship between co-opetition and product innovation performance. Technological capability and alliances with universities were shown to weaken the relationship. The findings add significantly to the emerging literature on dynamic co-opetition.