rofessional team-based learningthe kind that has the goal of achieving quality implementationrequires more than just time and space for teachers to meet. The type of collaboration indicative of quality implementation is what we refer to as joint-work. We borrow this term from Judith Warren Little's (1990) seminal article in which she calls for a harder look at what is meant by collaboration and the circumstances that foster or inhibit it. Little notes that teachers' collaborations range from sporadic contacts among peers to "joint-work of a more rigorous and enduring sort" (p. 513). Joint-work involves teachers engaging in "deliberation over difficult and recurring problems of teaching and learning" (p. 520) in the service of finding a better way. When high-powered teams come together, they focus their time on identifying and collaboratively solving the problems that are rooted in the learning needs of their students. These teachers' work involves an interdependence, where motivation to participate is based on the fact that each other's contributions are required in order to succeed. In 2002, Gully and his colleagues published a meta-analysis demonstrating that the relationship between collective efficacy and team performance is maximized when there is greater positive interdependence among the members of the team. Little notes that joint-work is about the acceptance of shared responsibility: "Professional autonomy and discretion reside collectively with the faculty; put more forcefully, each one's teaching is everyone's business, and each one's success is everyone's responsibility" (p. 523)