Effective supervision models guide the supervisory relationship and supervisory tasks leading to reflective and purposeful practice. The Developmental/Ecological/Problem-Solving (DEP) Model provides a contemporary framework for supervision specific to school psychology. Designed for the school psychology internship, the DEP Model is also applicable to all pre-service and advanced field-based training, as well as career-long continuing professional development. The Developmental domain initiates training at the functioning skill level of the supervisee and progresses toward independent competency. The Ecological domain addresses the multiple systemic contexts that influence school psychology practice and prepares the intern to intervene within both individual and systemic contexts. The Problem-Solving domain focuses on the application of data-based decision making and evidence-based interventions to the full range of school psychology activities. It provides a systematic schema to address student, family, and school needs.