This paper examines gender differences in the participation of university life science faculty in commercial science. Based on theory and field interviews, we develop hypotheses regarding how scientists' productivity, co-authorship networks, and institutional affiliations have different effects on whether male and female faculty become "academic entrepreneurs". We then statistically examine this framework in a national sample of 6,000 life scientists whose careers span more than 20 years. We find sharp gender differences in participation in for-profit ventures, which we measure as the likelihood of joining the scientific advisory board (SAB) of a biotechnology firm. Compared to men, women life scientists are much less likely to advise for-profit biotechnology companies. We also identify factors that contour this gender difference, including scientists' co-authorship network structure and the level of support for commercial science at their universities. Surprisingly, we find that the (conditional) gender gap is largest among faculty members at the highest status institutions.