A major contributor to Reformed theology was John Calvin, who converted from Roman Catholicism after training for the priesthood and in the law. In exile in Geneva, Switzerland, Calvin developed the presbyterian pattern of church government, which vests governing authority primarily in elected laypersons known as elders. The word presbyterian comes from the Greek word, "presbyteros" which means "elder". The presbyterian form of government (rule by elders) evolved when the Reformers focused on both freedom and responsibility in the community of believers.

Elders are chosen by the people. Together with ministers of the Word and Sacrament, they exercise leadership, government, and discipline and have responsibilities for the life of a particular church as well as the church at large, including ecumenical relationships. They shall serve faithfully as members of the session. (G-10.0102) When elected commissioners to higher governing bodies, elders participate and vote with the same authority as ministers of the Word and Sacrament, and they are eligible for any office. (Book of Order G-6.0302)

The body of elders elected to govern a congregation is called a session. They are elected by the congregation and are representatives of the other members of the congregation. The session has overall responsibility for the direction, Christian education, and pastoral care of the congregation. Through ordination they are officially set apart for service. Their service term is for three (3) years, but they are ordained for life. Ministers (pastors and associate pastors) who serve the congregation are also part of the session. The session is the smallest, most local governing body. The other governing bodies are presbyteries, which are composed of several churches; synods, which are composed of several presbyteries; and the General Assembly, which represents the entire denomination. Elders and ministers who serve on these governing bodies are also called "presbyters".

The General Assembly meets once a year and is the highest court of the church. It receives reports and recommendations from its Agencies and Committees. It also receives and debates petitions, overtures, references, complaints, appeals from the entire Church and establishes committees when issues require further study. It also elects a Moderator who presides over the Assembly, and continues in an inspirational and ceremonial role for the following year. The General Assembly is the main decision-making body of the Presbyterian denomination.