Robinson et al. (2008) grouped measurement items to reflect common leadership practices. From 27 studies published between 1978 and 2006, the authors found that practices associated with establishing school goals, supervision of instruction, and professional learning were highly impactful and concluded, “the more leaders focus their relationships, their work, and their learning on the core business of teaching and learning, the greater their influence on student outcomes” (Robinson et al., 2008, p. 636).