The session governs a particular congregation. It is made up of elders elected by the congregation, plus all the installed pastors on the staff, including pastors, co-pastors, and associate pastors.
(G-10.0101)

The session is responsible for all decisions regarding the program and policies of its congregation, except for the two powers reserved for the congregation: the election of officers, including the pastoral staff, and the buying, selling, and/or mortgaging of church property. The constitution spells out 19 specific duties for the session.
(G-10.0102, G-7.0304)

The session is composed of elders elected for specific terms of service as well as the installed pastor(s) and associate pastor(s). It is presided over by the moderator, who is the pastor or a minister member of the Presbytery when the pastor is not available.
(G-10.0101, G-10.0103, G-14.0201)

The session elects its own clerk, who is called "Clerk of the Session." The clerk of the session must be an elder, but not necessarily one serving currently on the session. The session elects the clerk for such term as it shall determine. The clerk of the session has many duties regarding the records of the church, and also serves as secretary of meetings of the congregation.
(G-9.0203, G-10.0300)