Teamwork is an important component of engineering education programs; however, when not facilitated well, it can be a site of gender biases. The aim of this article is to thematically explore what and how engineering professors think about gender in the assessment of teamwork. In 2014 and 2015, semi-structured interviews were conducted with 39 engineering professors in the United States. Interviews covered a wide range of topics, with one section of the interviews devoted to teamwork specifically. For this article, the parts of the interviews about assessment of teamwork are analyzed. It was found that most participants were unaware of the ways in which gender can influence assessment and did not attempt to mitigate biases in self-evaluation, peer-evaluation, or team presentations. Recommendations for best practice are offered.