Instructional leadership, which occupies the greatest proportion of all school and management theories, possesses strong empirical roots (Hallinger, 2012). Research in the 1970 s on successful schools constantly found that effective schools had principals who were particularly concerned with and spent time on improving the teaching and learning aspects of the school (Austin, 1979; Brieve, 1972; Bridges, 1967; Duke & Stiggins, 1985; Edmonds 1979; Eberts & Stone, 1988; Hallinger & Heck, 1996; McKenzie, 1988; Niedermeyer; 1977). In contrast to principals who spend most of their time dealing with managerial issues such as the budget, paper work, and the implementation of rules and regulations, principals in effective schools direct their attention more toward the academic aspects of their schools, such as setting academic goals, developing curriculum, assessing the effectiveness of teachers' practices, and providing opportunities for improvement. Such behaviors associated with the principals of effective schools are defined as instructional leadership (Blase, 1987; Blase & Blase, 1999; Bossert, Dwyer, Rowan & Lee, 1982; Bridges, 1967; Hallinger, 2001, 2003, 2011, 2012; Marks & Printy, 2003; Hallinger & Murphy, 1983, 1985, 1987; Hallinger, Murphy, Well, Mesa, & Mitman, 1983; Rosenholtz, 1985; Southworth, 2002).Since the development of the theory in the 1980's, has been a substantial focus of educational research and was finally placed at the top of the list among all theories (Hallinger, 2013). Early researchers mainly concerned themselves with the development of significant conceptual knowledge (how one might clarify and define leadership) and theoretical understandings of the value and influences of (Bossert et al., 1982; Hallinger & Murphy, 1985; Murphy 1990; Petterson, 1993; Weber, 1996). Later research investigated the contribution of on teacher and student learning (Blase & Blase, 1999; Gerrell, 2005; Hallinger, 2011; Hallinger et ah, 1983; Hallinger, Bickman, & Davis, 1996; Hallinger & Heck, 1996, 2011; Heck, 1992; Heck, Larsen, & Marcoulides, 1990; May & Spovitz, 2011; Leithwood, Day, Sammons, Harris & Hopkins, 2006; Leithwood & lantzi, & Steinbach, 1999; Robinson, Lloyd & Rowe, 2008; Sebastian & Allensworth, 2012; Supovitz, Sirinides, & May, 2010). Ultimately, in a comprehensive study drawing on longitudinal data derived from hundreds of schools in Chicago, Bryk, Sebring, Allensworth, Luppescu, and Easton (2010) listed as an indispensable component of school principalship which was found to be a significant driving force for schools in achieving high quality instruction and thereby enhancing student achievement.The significance of has been recognized by educational policy makers, practitioners, and international organizations such as the Organization for Economic Co-operation and Development (Hallinger, 2012; OECD, 2009). Many countries have required principals to work with teachers towards the betterment of curriculum and practices. In the USA, principalship standards, which are determined at the state level, overwhelmingly emphasize involvement in the design and implementation of high quality practices that better fit student needs. For instance, Colorado principal-quality standards require principals to establish high standards for curriculum and instruction, support teachers through continuous feedback and professional development, help teachers maximize effective use of time, and work with teachers to determine the best practices which are research-based and address student needs (Colorado Department of Education). Similarly, the Turkish Ministry of National Education (MoNE) passed a law in 2010 that required school principals to exhibit multifaceted roles, such as developing their school's vision and mission, observing teaching and learning activities, and providing feedback to teachers regarding their performance, all in order to ensure high quality teaching and learning (MoNE, 2010). …