Innovating firms are likely to face several challenges and experience different types of barriers. In this paper we argue that it is necessary to distinguish between two kinds of barriers to innovation. The first corresponds to what we describe as revealed barriers and reflects the degree of difficulty of the innovation process and the learning experience consequent on the firm engaging in innovation activity. The second type of impediment, which we label deterring barriers, encompasses the obstacles that prevent firms from committing to innovation. We use data from the 4th UK Community Innovation Survey (CIS4) to investigate the relationship between firms§ engagement in innovation and their assessment of the barriers to innovation. We show that the relationship is curvilinear in the case of costs and market barriers. These results have important implications for innovation policy and innovation management. © 2011 Elsevier B.V.