Firms striving to maintain high rates of innovation need a continuous flow of new ideas. This is resulting in the establishment by large firms of IT platforms to generate ideas for innovation, and to encourage employees and customers to participate in innovation contests. However, there has been little published research on the use of IT platforms for idea generation by employees, and it is unclear whether they facilitate in-house innovation. The purpose is to investigate how firms use IT platforms internally to generate ideas, and how their use contributes to the innovation process in large firms. We rely on data from two collaborative research projects in the automotive industry: Volvo Cars and Renault. We found that both firms used IT platforms as campaigns to promote innovation and to involve employees in the innovation process. The findings suggest that these virtual idea campaigns support innovation in large firms mainly by (1) encouraging employee creativity in idea generation and (2) involving employees and top managers simultaneously in the innovation process. This paper contributes to idea management systems theory by highlighting the importance of virtual idea campaigns for the firm's innovation process, and their dual role.