Supporting teachers' attention and responsiveness to the substance of student thinking is increasingly emphasized across disciplines. Yet studies demonstrate how such responsiveness, in practice, is highly contextualized and often fleeting. This study conceptualizes and examines what functioned as "resources for responsiveness" within and across nine sustained cases of responsiveness in three science teachers' inquiry-oriented classrooms. Analyses demonstrated how a diverse range of personal, social, and material/structural resources facilitated teachers' responsiveness, with some commonalities but also much variation across teachers. These findings contribute to the field's understanding of what may support teachers' attention and responsiveness to student thinking and suggest the importance of (a) responsiveness in the design and facilitation of professional learning and (b) increased attention to teachers' affect.