Pentecostalism grew from the Holiness movement — itself a child of the Methodist revival — and its longing for a deeper work of the Spirit. Its defining moment came at the Azusa Street revival in Los Angeles in 1906, where, under William J. Seymour, believers experienced what they understood as the baptism of the Holy Spirit, marked by speaking in tongues.
The movement spread with remarkable speed. It emphasized the present-day reality of the gifts of the Spirit — tongues, prophecy, healing — and a worship marked by expectancy and fervor. Out of it came denominations such as the Assemblies of God and the Church of God in Christ.
Within a single century, Pentecostal and related charismatic Christianity grew from a storefront mission to hundreds of millions of believers worldwide — one of the fastest expansions in the history of the faith. Its lineage runs back, through the Holiness movement, to the Methodist revival.