Ideas must become legitimate within organizations in order to get through the decision making in front-end of innovation (FEI) and reach the actual product development stage and finally commercialization. This paper presents an empirical study on legitimacy building through intelligence generation activities. The empirical material consists of 40 interviews gathered in R&D departments of three companies. In our study we found that customer orientation activities and more specifically, intelligence generation is a powerful means to acquire legitimacy for ideas in FEI. Through these activities the acceptance of ideas may be advanced either intentionally or unintentionally. We identified six different ways through which intelligence generation legitimates ideas in FEI: (1) commitment of developers and internal customers to the product, (2) avoidance of resistance towards the product, (3) facilitation of future efforts, (4) concretization of technological potential to decision makers, (5) demonstration of developers' technological capabilities to decision makers, and (6) sustaining decision makers' interest towards the idea. Previous research presents ways to gather understanding about customer needs and preferences in order to develop products that cater to those needs as well as acquire an understanding of possible market potential. This study shows that these activities have a larger impact on organizations by providing means for achieving acceptance for the ideas. In this paper we show a previously unrecognized outcome for intelligence generation activities and demonstrate concrete examples of the exploitation of these activities in organizations. The objective of legitimation of ideas through customer orientation activities has not been discussed in previous literature, thus this study widens the understanding of the objective and impact of customer orientation in FEI. This research brings into attention that intelligence generation is a powerful mechanism through which ideas are legitimated to internal customers, developers and decision makers, and trust towards developers is created.