Many prior studies have explored average differences in initial levels of teaching effectiveness among graduates from different teacher preparation programs (TPPs) and the features of preparation that predict these differences. We focus on another important dimension of effectiveness--how graduates from different TPPs improve over time. Examining all graduates from Tennessee TPPs from 2010 to 2018, we find meaningful differences between TPPs in both initial level and early-career growth in teaching effectiveness. We also find that different TPP features explain part of these differences. Yet the features that correlate with initial teaching effectiveness are not the same features that correlate with growth. This article informs policy decisions around TPP evaluation and identifies new directions for future research in TPP effectiveness.