This paper delves into STEM (science, technology, engineering, and mathematics) Ph.D. students’ relationships with their advisors. Through in-depth, semi-structured interviews, late-stage graduate students in STEM fields describe characteristics of their primary advisors as well as the dynamics of their relationships with them. From these narratives we construct an “ideal type” advisor. Weber’s notion of an ideal type is a conceptual heuristic that reflects or encompasses essential characteristics of a phenomenon in order to generate a “pure” type that is then examined against reality. In this analysis we propose that an ideal type advisor offers students departmental and disciplinary moorings, career and program advice, and mentoring. As we develop this construct, we examine the consequences for students of having or not having advisors that approximate the ideal type. An emphasis on gender highlights how women’s experiences differ from men’s. Recommendations for advisors, departments, and graduate programs are also offered.