Much attention over the past decade has been given by policy makers to the importance of data-driven decision making and evidence-based practices in education (Aguerrebere, 2009; Cilbulka, 2013; CCSSO, 2012; Duncan, 2009, 2010, 2012; Easton, 2009, 2010; National Council for Accreditation of Teacher Education, 2010). And much has been written about data-driven decision making in recent years. The field has seen special issues of journals (Coburn & Turner, 2012; Turner & Coburn, 2012; Wayman, 2005a, 2005b, 2006), edited books (Herman & Haertel, 2005; Kowalski & Lasley, 2009; Mandinach & Honey, 2008; Moss, 2007), focused books (Boudett, City, & Murnane, 2007; Mandinach & Jackson, 2012; Supovitz, 2006), research syntheses (Hamilton, Halverson, Jackson, Mandinach, Supovitz, & Wayman, 2009), and federally funded landscape studies (Means, Chen, DaBarger, & Padilla, 2011; Means, Padilla, & Gallagher, 2010). Yet the field is still emerging. There is much we know (Hamilton et al., 2009), and there is also much we do not know (Mandinach, 2012; Marsh, 2012; Turner & Coburn, 2012) or that has methodological challenges. Even some of the most rigorously designed studies about impact result in interpretive questions (Carlson, Borman, & Robinson, 2011; Konstantanopoulus, Miller, & van der Ploeg, 2013).