Background/Purpose: Residents play an important role as teachers of junior colleagues and medical students. Clinical teaching also helps residents in clinical learning. However, the skills required for residents to be competent teachers are rarely described systemically. Beyond the widely adopted six core competencies for postgraduate training by the Accreditation Council for Graduate Medical Education (ACGME), the teaching competencies should be further developed, and the milestones should be clearly defined to serve as better references for resident training programs. Methods: Twenty members, including five experts from major teaching hospitals across Taiwan and 15 from a public medical center, were invited to a workgroup to collaboratively develop a competency-based framework. The development process was similar to that suggested by the ACGME. The teaching competencies framework were drafted by an experienced physician educator. The draft was sent to each group member, and feedback was collected. Two workgroup meetings were held for consensus formation. The contents of the teaching competencies of residents were confirmed after two rounds of revision. The outline of the framework was also reported at an international meeting in September 2019. Results: Two core competencies, instruction and assessment, with three sub-competencies and 37 milestones, were adopted in the final edition of resident-as-teacher competencies. The sub-competencies were “dissemination of knowledge” and “teaching of procedural skills” for instruction, and “direct observation and feedback” for assessment. Conclusion: A competency-based framework for resident-as-teacher was developed. The framework can be applied in combination with other existing competencies for holistic postgraduate training programs.