Two approaches to setting standards for the professional performance of teachers are contrasted. One involves a coherent professional belief system in which an internal standard is invoked within a conceptual framework. It is exemplified by Sigel's Distancing Model, and involves a theoretical standard for teacher performance and emphasizes the role of self-assessment in the professional development of teaching knowledge and skill. A teacher observation instrument is developed and designed to provide the teacher's own perception of instruction, curriculum and cognitive/social/affective dimensions of development. The second approach involves the standardized measurement of teacher knowledges and skills deemed essential for entry-level teacher competency. Examples such as the National Teacher Examinations (NTEs) are judged against standards determined by a content review process and a knowledge estimation panel (i.e., a jury approach). Expanded sources of validation for determining baseline teacher competencies are needed to link competence with performance and are discussed in relation to the planned short-term and long-term revision of the NTE Commons. (Author/RL)