The Acts of the Apostles historically and geographically demonstrates how churches were planted from Jerusalem to the ends of the earth through the Gospel message which the apostles were called to preach. The apostles witnessed Jesus Christ as their personal Saviour and Lord who was crucified and resurrected by the power of the Holy Spirit in accordance with God's will. This study attempts to point out some missiological themes revealed in Acts and to apply them in mission studies and on the mission fields. First, Acts demonstrates that the Gospel message was preached and the churches were planted in various countries through out Asia and Europe by the power of the Holy Spirit. Both dimensions of "seeing" and "hearing" the Gospel message were rarely illustrated apart from the work of the Holy Spirit. The apostles Peter and Paul, as well as laity like Stephen and Phillip who were filled with the Holy Spirit, courageously preached the Gospel message. As a result, the Gospel message was finally communicated to Rome, the end of the world at that time. Second, Acts seeks universality in terms of Gentile missions. The Gospel message whose essence is the crucifixion and resurrection of our Lord Jesus Christ is the salvific message which is able to save all humans whether they are Jew or Gentile. The apostle Peter realized the significance of Gentile missions through the vision of meal and the apostle Paul through the Lord's voice on the way to the city of Damascus. The Gospel message was communicated across races, cultures, languages, and lands. Third, Acts confirms that Gentiles did not have to become culturally Jewish to be saved. In other words, they did not need to be circumcised to become a Christian. What they needed to do to be saved was to repent of their sins and to accept Jesus Christ as their personal Savior and Lord. Acts solidifies the principle of justification by faith. Further, Acts maintains that people can become Christians in their own culture. Fourth, Acts shows that the apostle Paul preached the Gospel message in the city of Athens. At that time, Athens was an open city and the center of philosophy and religion. Paul contextualized the Gospel message of Jesus Christ in the city. For example, he cited Greek poems when he preached the Gospel message to the Greeks in the meeting of the Areopagus so that the Greeks could easily understand the Gospel message. Consequently, some Greeks became Christians. However, Paul attempted critical contextualization. Fifth, Acts reveals that the Apostle Paul carried out urban missions throughout Asia and Europe. Paul chose central cities in various areas in accordance with the guidance of the Holy Spirit and reached the different people groups in the central cities. The people in the cities would be more open than the people in the rural areas to the Gospel message of Christianity. Acts reveals that urban evangelism was more effective. Sixth, Acts is regarded as a historical book of the church. The early churches planted by some apostles experienced considerable growth numerically, geographically, and spiritually. Church growth demonstrated in Acts is biblically healthy and has balanced growth. The essence of church growth is to make Christlike disciples in every nation and to make them responsible members of the church. The apostle Paul not only planted churches but he also nurtured believers as Christlike disciples. As a result, churches became indigenized in different cultures. Evangelism and missions are God's strong desire. God not only seeks sinners but also finds them. He sent His only begotten Son to the world and let Him die on the cross to save the lost. He saves people who truly repent of their sins and accept Jesus Christ as their Saviour and Lord. Acts is the book which discusses the process of evangelization and church planting from Jerusalem to the ends of the earth with the power of the Holy Spirit and in accordance of God's salvific plan. Churches today need to continue the work started in the Acts of the Apostles.