Success in any field depends on a complex interplay among environmental and personal factors. A key set of personal factors forsuccess in academic settings are those associated with self-regulated learners (SRL). Self-regulated learners choose their own goals,select and organize their learning strategies, and self-monitor their effectiveness. Behaviors and attitudes consistent with self-regulated learning also contribute to self-confidence, which may be important for members of underrepresented groups such aswomen in engineering. This exploratory study, drawing on the concept of ‘‘critical mass’’, examines the relationship between thepersonal factors that identify a self-regulated learner and the environmental factors related to gender composition of engineeringclassrooms. Results indicate that a relatively student gender-balanced classroom and gender match between students and theirinstructors provide for the development of many adaptive SRL behaviors and attitudes.