Tools are needed to track the elements of students' successful engagement in inquiry. The "McGill Strategic Demands of Inquiry Questionnaire" (MSDIQ) is a 79-item, criterion-referenced, learner-focused questionnaire anchored in Schon's model and related models of self-regulated learning. The MSDIQ addresses three phases of inquiry engagement--planning, enactment, reflection--perceived as important by teachers, parents, and students before or after inquiry participation. Internal consistency and validity evidence was obtained from 205 university students with different inquiry backgrounds: teacher education years 1 and 4, continuing teacher education, and honors psychology. Separate confirmatory factor analyses of planning, enactment, and reflection generated 14 intercorrelated factors congruent with definitions of inquiry instruction and supported the hypothesized structure underlying the MSDIQ as a reliable and valid instrument for measuring inquiry engagement and valuing its building blocks.