Academic scientists are encouraged to pursue research that delivers both scientific and societal impact. This may involve a search for alternative mechanisms of social approval which lead to endorsement of scientists’ research goals. We explore how scientists mobilise and accumulate different forms of legitimacy, which might favour their participation in practices related to innovation and societal impact. We propose three specific sources of scientific legitimacy: i) scientists’ social networks (research-related legitimacy ties), ii) prominence in the relevant academic community (reputation-based legitimacy); and direct contact with the primary beneficiaries of the research (beneficiary-based legitimacy). To explain scientists’ participation in activities oriented towards innovation and societal impact, we test the significance of each of these sources of legitimacy and their potential interplay empirically, using a large sample of Spanish biomedical scientists.