Customer integration into the innovation process is about to become a best practice. The lead-user approach has proven to be especially valuable when reducing discontinuous innovation's market risk. Since the theory of customer integration still lacks a concept and processes, this article illustrates how companies can be helped from a practice perspective to implement customer integration to maximum market safety. Triggered by the results of an in-depth case study, we adapted Lettl's (2004) explorative model of customers' contribution to the new product development (NPD) process to engineering companies from its original background in the medical technology industry.