Common experience, along with a vast collection of research, demonstrates that schools can expect a range of benefits to accrue when teachers work together. Teacher teaming can reduce teacher isolation, increase collegiality, facilitate the sharing of resources and ideas, and capitalize on teachers’ individual and shared strengths. And most recently, teacher teaming has been “discovered” as an avenue toward teacher learning and enhanced professional development that can lead to gains in student achievement. We’ve been working in and studying teacher teams for more than two decades, and our current work focuses specifically on analyzing the elements of effective teacher teams. So far, we have found very few teams that can truly be called effective in every sense. The reasons for this are many and vary