In 2017, the National Technical Assistance Center for the Education of Neglected or Delinquent Children and Youth (NDTAC) released its first in a series of professional development briefs that focus on the professional development needs and interests of neglected or delinquent (N or D) State coordinators, correctional educators, and providers of Title I, Part D (Part D) programs and services. These briefs are intended to inform the planning, design, and delivery of professional development for individuals working in Part D and correctional education programs. This third professional development brief seeks to foster a shared understanding of the fundamentals for creating and sustaining safe and supportive learning environments in juvenile justice settings and includes potential ideas for professional development offerings that may enhance the conditions for learning plus social and emotional learning (SEL) opportunities. [For the first and second briefs in this series see ED577000 and ED577001, respectively.]