In this case study, we investigate upper elementary teachers' decision-making practices regarding grouping configurations and purposes set for small group instruction (SGI) across content areas. Five experienced teachers working in linguistically and culturally diverse settings participated in this study. Data analyses with regard to student grouping revealed that, depending on the subject area, tasks, and "nonacademic" considerations, teachers navigated among multiple SGI setups, including similar- and mixed-ability groups, performance- or current-needs-based groups, and--unique to one teacher--a fluid-stable configuration. Data analyses with regard to purposes for SGI instruction revealed that although targeting disciplinary literacy was the main reason for SGI, it also served as a tool for (a) gauging students' needs and how students responded to instruction, (b) "hitting" multiple within- and cross-disciplinary targets, and (c) building students' social skills. We refer to these teacher decision-making practices as "organizational fluidity" and "focal fluidity," respectively. Implications are discussed.