The developmental trajectories of participants (N=1315) engaged in team-based action learning projects (k=205) to promote leader development were estimated using two classes of growth modeling techniques. Evidence was found in support of differences in the initial leadership effectiveness levels across participants as well as differences in the shape or form of their personal trajectories. Based on recent theorizing on leader development (Day Harrison & Halpin 2009) it was predicted that adopting a leader identity would serve as a within-person time-varying covariate of leadership effectiveness and that goal orientation would serve as a between-person cross-level moderator of the personal change trajectories. Results suggested full support for the role of leader identity and partial support for goal orientation. The results of growth mixture modeling analyses revealed two distinct latent classes of developmental trajectories that could be distinguished empirically by one type of adult development processes (i.e. selection). Results are discussed in terms of advancing leader development science and practice especially with regard to the insights gained from charting and understanding leaders' developmental trajectories.