This study develops a contingency framework by drawing upon on the perspectives of resource-based view, stakeholder, and open innovation to investigate how and when market demand, environmental proactivity, and technology competence affect a firm's decision on the scope of eco-innovation. A sample composed of 1,717 service firms is utilized to test the hypotheses. A zero-truncated negative binomial approach is adopted to analyze the data. The results reveal that innovation openness plays a significant moderating role in the influence of proactivity and technology competence on the scope of eco-innovation. Specifically, environmental proactivity has a stronger effect on the scope of eco-innovation under high levels of search breadth and depth. Moreover, technology competence has more influence on the scope of eco-innovation under a high level of search breadth. In addition, the results reveal that market demand positively affects the scope of eco-innovation.