In this quotation, Lieberman and Pointer Mace not only summarize the core of what scholars and practitioners have learned about ‘effective teacher learning and development’ but also identify the ‘heart of successful education reform’. Education reforms implemented throughout the world over the past several decades have challenged educators to adapt to a rapidly changing world. Yet, fundamentally, education systems cannot meet these challenges of change unless the educators in our schools are capable of adapting to new perspectives, knowledge and skills (Borko, 2004; Vescio, Ross, & Adams, 2008). Thus, Lieberman and Pointer Mace (2008) concluded that teacher learning 'on-the-job' is the key to unlocking the untapped potential of educational reform.