This book approaches the study of the Holy Spirit from a unique biblical perspective. It presents the Holy Spirit as "God's Missionary Spirit," focusing on the central role of the Holy Spirit in fulfilling God's mission to call to himself a people out of every tribe, language, and nation on earth. It is designed to equip church leaders to better guide their churches into authentic New Testament experience and practice. It is further designed to help leaders mobilize their churches for Spirit-empowered mission and church planting. The author believes that, if the church is to fulfill its God-ordained destiny among the nations, it must capture a missional understanding of the person and work of the Holy Spirit. It must fully embrace Jesus' last message to the church: "But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth" (Acts 1:8).