This study contributes to the team development and effectiveness literatures by exploring the activities and outputs of three high performing and three low performing ad hoc project teams from initiation to project completion. While, all six teams progressed through four common phases of development, the high and low performers exhibited several striking differences in the specifics of their activities and outputs at various points along the way. Most notably, the high performing teams got things right from the start and subsequently progressed steadily, if not smoothly, through the remaining phases of development to ultimate success. In contrast, the low performing teams stumbled in the early going and never really recovered. Based on these findings, we suggest that researchers, as well as team leaders, have much to gain from devoting considerably more attention to the ways in which project teams are mobilized and launched.