As a teacher, McKay was highly popular and effective, and he was greatly concerned that students stretch their minds beyond the facts and into the world of ideas. He believed that it was also a teacher's responsibility to help students develop the kind of moral and ethical values that lead to responsible citizenship. As a church leader he once scolded the nation for not recognizing the importance of paying for outstanding teachers.
After his call to the Quorum of the Twelve Apostles in 1906, McKay continued as head of Weber Academy until 1908, then served on the institution's board of trustees until 1912. He also served on the University of Utah's Board of Regents from 1921 to 1922, and on the board of trustees of Utah State Agricultural College from 1940 to 1941. He was superintendent of the LDS Church Sunday Schools from 1918 to 1934, and in 1919 he became the church's first Commissioner of Education. In that capacity he recommended the closing of most of the church's academies, which had been operating since the nineteenth century but by 1920 seemed almost superfluous because of the growth of public high schools in Utah. In their place the church established seminaries adjacent to high schools with sufficient LDS students. These would provide voluntary, week-day religious education, usually on a released-time basis.
McKay's early experiences as an apostle undoubtedly had an impact on the broad, international outlook that later characterized his presidency. He toured the missions of the world from 1920 to 1921, and from 1922 to 1924 he served as president of the European Mission. There he revitalized missionary work and, emphasizing his international perspective, urged the European Saints to stop migrating to America. Rather, he told them, they should build up the church in their homelands, and he promised them that one day all the programs of the church, including temples, would be available to them.