Firms are increasingly involving users in new product development (NPD). Their product users frequently provide solution information, such as new product ideas. However, these users are often considered a homogeneous group of ordinary users; their individual abilities and the specific input they provide for NPD are not yet well understood. The goal of this paper is to determine whether different types of users are differently predisposed to produce ideas. We derive hypotheses regarding the possible outcome of involving different user types in idea generation tasks from the current literature on customer integration into NPD. In a quasi-experimental setting, we test our assumptions on 93 users, who generate ideas in a smart home context. The results indicate that users’ contribution depends on their specific domain knowledge, which is broadly understood as knowledge of a specific area that influences ideation towards solutions in this domain. We distinguish between four types of users: those with high trend awareness, high technical skills, high technical innovativeness, and high ethical reflectiveness. We find that users with high technical skills are more likely to produce ideas that are technically feasible. Trend-aware and technically innovative users produce ideas of greater originality. Ethically reflective users tend to come up with ideas that will have a positive impact on society.