This study contributes to the understanding of New Product Develop­ment (NPD) performance by demonstrating how formal interfirm collaborative relationships provide access to important information and how the structure of the formal interfirm network impacts NPD in different ways. The study also develops a dimension of networks, network diversity, and its contribution to NPD performance. In ex­ploring how NPD performance is affected by information available between firms with formal cooperation agreements, it suggests that two aspects of the formal external information network, variety and control, have an impact on a firms NPD performance. Network theory is used to understand information variety and control during NPD. Analyzing a firms egocentric network of formal relationships provides insight about information availability. Egocentric network diversity serves as a proxy for variety of information and egocentric structural holes (connectedness) provide an understanding of information control. The study shows that each of these factors has a differing relationship with three dimensions of NPD performance: innovative­ness, speed, and market performance.