Recent research on the professional competencies of mathematics teachers has conceptualized teacher professional competences from both a cognitive (e.g., knowledge and beliefs) and a situated perspective (e.g., teacher noticing). In this chapter, we first discuss three approaches to conceptualizing the construct of teachers’ professional competence, namely, behaviorist approaches, cognitive approaches, and the integration of cognitive and situated approaches. Second, findings related to the cognitive aspects of teacher professional competences such as the distinction of various components of beliefs and teacher knowledge, including mathematical content knowledge and mathematical pedagogical content knowledge, are systematically described. Third, findings identified in recent studies on the situated aspects of teacher professional competence are reviewed, examining the strengths and weaknesses of teacher noticing, the differences of the growth of teacher noticing including expert-novice comparisons, and the relationship between teacher knowledge and noticing under a cultural perspective comparing Eastern and Western educational cultures. Finally, identified differences and similarities are further discussed systematically from social and cultural perspectives and possible interpretations concerning the differences of students’ mathematics achievements identified between Western and Eastern countries are developed.