“…However, despite widespread agreement about the need for this support of early childhood educators, little empirical research exists to guide policymakers and educators regarding the type, intensity, and duration of professional development that is most effective in helping early childhood educators acquire and implement background knowledge and mastery in instructional strategies that lead to improved child outcomes (Maxwell, Field, & Clifford, 2006;Snow, 2006). Although several previous studies have attempted to affect teachers' language and instructional behaviors within the classroom via professional development (Dickinson & Brady, 2006;Dickinson & Caswell, 2007;Girolametto, Weitzman, Lefebvre, & Greenberg, 2007;Landry, Swank, Smith, Assel, & Gunnewig, 2006;O'Connor, 1999) and have reported changes in classroom environments and some teacher behaviors (i.e., book reading, environmental print, and use of abstract language), these studies either did not measure or found no or only small changes in child outcomes.…”