Social innovation is concerned with social mobilization and impact, and is increasingly seen as an option to address sustainability challenges. Nevertheless, the concept of social innovation is quite open in character and requires empirical accommodation to establish how it differs from other types of innovation in this setting. This article contributes empirically to the concept of social innovation as it reviews categories of success factors of social innovation against those of five other innovation types (product, service, governmental, organizational, system) in 202 innovation cases that focus on climate action, environment, resource efficiency and raw materials. Statistical analysis with contingency tables is applied to examine the distribution of five kinds of success factors across the innovation types: economic, environmental, political, social, and technological. The results confirm empirically that social innovation is indeed a distinct type of innovation. There are statistically significant differences in the distribution of categories of success factors between social innovation on the one hand and product, service and governance innovation on the other. In addition to the prevalence of social success factors, social innovation is characterized by a lesser emphasis on political and technological success factors.