The Community for Advancing Discovery Research in Education (CADRE) Early Career Guide offers advice on becoming a successful researcher in the field of STEM education and a portrait of an early career researcher support program. The advice offered throughout the guide comes from experienced researchers who are part of the National Science Foundation's Discovery Research PreK-12 (NSF DRK-12) community. The guide is divided into three parts. Parts I and II offer tips and resources to address the needs of STEM education researchers who are early in their careers, primarily doctoral students and research associates. These materials are organized around four focal themes: (1) pursuing academic and non-academic career pathways; (2) writing for publication; (3) building professional networks; and (4) developing NSF proposals. Early career researchers may choose to independently access the resources in Parts I and II on an as-needed basis or pick from the resources and other elements of the Fellows program (described in Part III) to share with, for example, a study group with other graduate students and professional peers. Building on Parts I and II, Part III describes a model for supporting early career STEM education researchers based on the CADRE Fellows program, and provides strategies and resources to guide those who supervise, advise, or mentor groups of early career STEM education professionals. Part III offers a detailed description of the structure and objectives of the CADRE Fellows program and the design of the activities within the focal themes. It also provides insights into the impact of the program. The guide is organized in such a way that advisors, supervisors, mentors, and program leads who work with early career researchers can choose those elements from Parts I, II, and III that are most appropriate and use them to develop customized supports to use on an ad-hoc basis or in the formation of a more formal early career researcher program. Early career researchers might also choose to use several of the guiding questions associated with each strand in Part III when talking with more-experienced researchers, or work on one of the assignments independently or with another colleague.