Four studies examine the faculty–student relationship as a mechanism through which students ascertain their place in science, technology, engineering, and mathematics (STEM) fields. Studies 1 and 2 use experimental methods to demonstrate STEM faculty who behave communally, relative to independently, increase undergraduates’ belonging and interest in STEM roles through anticipation of greater role-specific support (i.e., support that emphasizes guiding students through structures and activities of field-specific roles). Study 3 then examined the consequences of role-specific support for undergraduates’ belonging and interest in STEM. Students anticipated more belonging and interest in STEM roles when faculty provided high levels of role-specific support. Finally, STEM doctoral students’ perception of role-specific support from faculty related to their belonging and future identification in STEM fields (Study 4). Taken together, these studies demonstrate the importance of students’ construals of role-specific support from faculty, and how faculty behavior signals role-specific support, with benefits for student involvement in STEM.