The importance of early and developmentally appropriate science education is increasingly recognized. Consequently, creation of common guidelines and standards in early childhood science education has begun (National Research Council (NRC), 2012), and researchers, practitioners, and policy makers have shown great interest in aligning professional development with the new guidelines and standards. There are some important issues that need to be addressed in order to successfully implement guidelines and make progress toward accomplishing standards. Early childhood teachers have expressed a lack of confidence in teaching science and nature (Torquati, Cutler, Gilkerson, & Sarver, in press) and have limited science and pedagogical content knowledge (PCK) (Appleton, 2008). These are critical issues because teachers' subject-matter knowledge is a robust predictor of student learning outcomes (Enfield & Rogers, 2009; Kennedy, 1998; Wilson, Floden, & Ferrini-Mundy, 2002) and is seen as a critical step toward improving K-12 student achievement (National Commission on Mathematics and Science Teaching for the 21st Century (NCMST), 2000; NRC, 2000). We argue that the same is true of preschool teachers. This chapter discusses: (a) theories and practices in early childhood science education (i.e., preschool through 3rd grade) in relation to teaching for conceptual change, (b) research on methods of professional development in early childhood science education, and (c) innovative approaches to integrating scientific practices, crosscutting concepts, and disciplinary core ideas with early childhood professional development.