This chapter, by David T. Crowther and Susan Gomez Zwiep, briefly outlines the challenges faced by leaders seeking to design and execute professional development that enables science educators to successfully implement the Next Generation Science Standards (NGSS). The chapter explores recent literature on NGSS-aligned professional development and describes the adoption process of two NGSS states—California and Nevada. Teacher background information, standards, assessments, references, and resources are provided. This book selection also includes the Table of Contents, Foreword, Preface, Acknowledgments, and Index.