However, the history of spiritual formation as a specific movement within 20th century Protestantism is possible. James Houston traces the history of the movement to post-Vatican II reformers within the Roman Catholic church, who sought to find ways to educate and train new priests in a manner that was appropriate to Vatican II ideals. This formative perspective began to spread into and was adopted by the Association of Theological Schools, and as an increasing number of evangelical schools began joining them in the 1970s and 1980s, the ideals spread throughout the academic and theological strata of Christianity, particularly in the United States. While initially aimed at academic and pastoral leadership, Houston notes that the Protestant ideal of the priesthood of all believers pushed churches to expand this formative ideal to all individuals.