Certification requirements for teaching have advanced with educational opportunity, although they vary widely from country to country. Some, like the United States, allow each state to establish its own requirements; others, like England, set national standards. The trend in certification has been toward requiring more complete training, with practice teaching and extensive graduate work for specialized positions. In many countries extension or summer graduate work is required of teachers or is made a prerequisite for advancement. A number of graduate professional degrees are now offered, including the Master of Arts in Teaching and the Doctor of Education. While the professional requirements for teaching in the United States have in the past stressed method and psychology, increasing emphasis is now being placed on subject-matter specialization; European countries have generally stressed scholarship.
Improvements in teacher training led to demands for professional recognition and benefits. These resulted in the formation of several international organizations as well as local and national teachers' unions. The success of teacher training for elementary and secondary education has led some college administrations to consider requiring such training for college teaching also.