Physician competencies have increasingly been a focus of medical education at all levels. Although competencies are not a new concept, when the Accreditation Council for Graduate Medical Education (ACGME) and the American Board of Medical Specialties (ABMS) jointly agreed on six competencies for certification and maintenance of certification of physicians in 1999, it brought about renewed interest. This article gives a brief overview of how a competency-based curriculum differs from other approaches and then describes the issues that need to be considered in the design and implementation of such a curriculum. In order to achieve success, a competency-based curriculum requires careful planning, preparation and a long-term commitment from everyone involved in the educational process. Building a competency-based curriculum is really about maintaining quality control and relinquishing control to those who care the most about medical education, our students. In the face of the many challenges that are facing undergraduate medical education (UME), including declining availability of teaching patients and over-burdened faculty, instituting quality control and relinquishing control will be necessary to maintain high quality.