Announcing his successor — Dallin H. Oaks — is largely a formality because the church has a well-defined leadership hierarchy that has governed it for decades. Here’s a closer look at how the leadership structure is arranged and how new members are chosen:Who leads the church? The longest was Brigham Young, who served nearly 30 years in the mid- to late 1800s. He and three other church presidents served less than five years, including an 18-month stint by Harold B. Lee from 1972 to 1973. Monson served nearly 10 years, and Hinckley was in the post for nearly 13.