A growing body of research has shown that women and students from other underrepresented groups often experience negative encounters and events when working on teams in engineering education. Given that teamwork is of central and increasing importance in developing future engineers, it is vital that engineering educators understand how to maximize gender inclusivity within their teamwork components. To that end, we created a training tool designed to help instructors facilitate more inclusive teamwork. This paper describes the collaborative development and content of a new, open-access, online training tool. The modules guide users through various ways in which teamwork can be problematic for women and other underrepresented groups. Users then complete activities in which they apply their newly gained knowledge to situations they might encounter in the classroom. Current efforts are now underway to disseminate the tool to engineering educators around the world.