Pentecostalism is arguably the most vibrant and rapidly growing religious movement of the 20th century, circling the globe in less than 25 years. Characterized by speaking in tongues, miracles, television evangelism, and megachurches, it is also known for its small-group meetings, empowerment of individuals, liberation of women, and humanitarian concerns. In this Very Short Introduction, William K. Kay outlines the origins and growth of Pentecostalism, looking at not only the theological aspects of the movement, but also the sociological influences of its political and humanitarian viewpoints. He shows that its history goes back to Methodism and, before that, to earlier revival movements, while its theology includes elements of holiness teaching and Adventism in a unique pattern focused upon Jesus. Worship may be expressed in innovative music or dance and, despite a worldview open to supernatural beings, believers are likely also to welcome the use of the latest communication technology. Kay discusses how Pentecostalism was joined in the 1960s by a new religious wave, the charismatic movement, which spilled over into mainline Christian denominations and transformed their worship.