This Workshop provides an opportunity for clinicians and those with training and supervisory responsibilities to intensively review the organizing principles of the Diagnostic Classification of Mental Health and Development Disorders of Infancy and Early Childhood – Revised, also known as DC: 0-3R™, a framework of developmentally informed, descriptive categories within a multi-axial system. This “hands-on� workshop provides an opportunity for intensive review of the developmentally and etiologically informed organizing principles of 0-3R™. It details a brief history of the development of the system and discusses the evolving use of the system for research, reimbursement, and clinical practice. Each axis is explained and demonstrated. Case presentations are discussed with an emphasis on diagnostic decision-making and case formulation.