This paper examines two contrasting knowledge-based antecedents of entrepreneurship and technology transfer among scientists in public research institutions. ‘Upstream knowledge sources’, which refer to insights for commercial opportunities gained as a result of high impact scientific contributions; and ‘downstream knowledge sources’, which refer to knowledge gained through researchers’ direct interactions with research beneficiaries. We find that downstream sources are associated with the two commercialization pathways examined: i.e. firm creation and technology licensing; while upstream sources are mainly associated with entrepreneurship (i.e. firm creation). Moreover, we find no evidence of a complementary relationship between upstream and downstream sources on academic entrepreneurship; while we find a substitution effect in the case of technology transfer. Our findings suggest the existence of three co-existing, alternative archetypes of academic scientists involved in firm creation: star scientists, engaged scientists and bridging scientists. In contrast, we find that downstream knowledge sources constitute the dominant knowledge-base antecedent to technology licensing.