Book excerpt: Implementation science is an important and underrepresented topic in the literature of educational research, despite the fact that it is inextricably tied to education policy and improvement. Implementation fidelity (the degree to which a program or intervention is delivered as planned) is, in particular, a key issue for every program developer and researcher designing, executing, interpreting, or communicating their work. Implementation Fidelity in Education Research provides the first serious developer-evaluator collaborative perspective on the practical considerations of implementation fidelity in program development. Using case studies from Investing in Innovation (i3) fund grants, this book prepares future researchers for the challenges posed by implementation issues both ideologically and in practice. This book will be an excellent resource for anyone interested in education research and evaluation and an excellent supplement to research methods courses.