Many active learning techniques have been used and described over the years, including team-based learning (TBL). While this technique is well established, it is only recently that analyses that compare it to other teaching techniques have been reported. In this paper, we evaluate the impact of team-based learning on two major concerns for computer science instructors: the drop/attrition rates, and students' success in CS1. The results show some major improvements both in terms of the drop rate and students' success, as measured by final exam grades. For example, the number of students obtaining 50% or more on the final exam has increased from 54% to 75.5%. Moreover, the drop rate has decreased from more than 30% to 6.4%.