The intuitive appeal of co-teaching belies the challenges faced in its design, implementation, and evaluation, as explicated in the increasing professional literature on this topic. From a clear conceptualization of what co-teaching is, through the still nascent research base demonstrating its impact on a variety of factors including professionals’ perceptions as well as student achievement and other outcomes, to the logistical and other challenges identified in co-teaching programs, these classroom partnerships illustrate the potential and complexity of collaboration as contemporary special education evolves to more deliberately and effectively integrate with general education.