Research summary: Existing research describes a broad range of determinants of new product development (NPD), a fundamental competitive activity of firms. A considerable share of this work has occurred in the context of developed economies, raising a concern that some important determinants may remain unexamined. We suggest that one such determinant is competition from informal (unregistered) firms. Drawing from the attention‐based view, we investigate the effects of informal competition on NPD in a large sample of firms located across Eastern Europe and Central Asia. We examine not only the direct effect but also how this effect is moderated by characteristics of the competitive and institutional context. Managerial summary: The purpose of this research is to examine the relationship between competition from informal (unregistered) firms and new product development (NPD) by formal firms. We argue that NPD is an effective response to differentiate from informal firms, and our analyses of over 9,000 firms located in emerging economies across Eastern Europe and Central Asia indicate that NPD activities are more likely in formal firms who rate informal competition as a greater obstacle. The strength of this direct relationship depends on aspects of the competitive and institutional environment: it is weakened when levels of competition from other formal firms are higher, when alternative responses such as corruption are more available, and when managers are more optimistic about the regulatory environment. Copyright © 2016 John Wiley & Sons, Ltd.