The First Apostolic Church of Sandwich is affiliated with the United Pentecostal Church International.
The United Pentecostal Church International (UPCI) has been among the fastest growing church organizations since it was formed in 1945 by the merger of the Pentecostal Church Incorporated and the Pentecostal Assemblies of Jesus Christ. From 521 churches in 1945, the UPCI in the United States and Canada grew to 4,305 churches (including daughter works and preaching points) and 9,193 ministers in 2011. In the same year it reported works in 193 nations outside the U.S. and Canada with 34,133 churches and preaching points, 19,686 licensed ministers, 748 missionaries, and a constituency of 2.2 million. The international fellowship consists of national organizations that are united as the Global Council of the UPCI, which is chaired by the general superintendent of the UPCI. Total constituency is estimated at 3 million.
The UPCI emerged out of the Pentecostal movement that began with a Bible school in Topeka, Kansas, in 1901 and with the Azusa Street Revival in Los Angeles, California, in 1906. It traces its organizational roots to 1916, when a large group of Pentecostal ministers began to unite around the teaching of the oneness of God and water baptism in the name of Jesus Christ. The governmental structure of the UPCI is basically congregational in that local churches are self-governing: the congregation elects its pastor and other leaders, owns its property, decides its budget, establishes its membership, and conducts all necessary business.
The general organization embraces a modified presbyterian system in that ministers meet in sectional, district, and general conferences to elect officials and to conduct business of the organization. The highest governing body of the UPCI is the General Conference, and between conferences it is governed by the Board of General Presbyters (General Board). Its chief officers are a general superintendent, a general secretary-treasurer, and two assistant general superintendents. World Evangelism Center is the UPCI headquarters building located in Hazelwood, Missouri, a suburb of St. Louis. It houses offices for its general officials, eight divisions, the Pentecostal Publishing House, and the Center for the Study of Oneness Pentecostalism with an attached gift shop. Among the endorsed institutions of the UPCI are eight colleges, a graduate school, an online ministerial training network, a children's home, a residency for troubled young men, a ministry to those addicted to alcohol and other drugs, an adoption agency with a home for unwed mothers, a chaplaincy for prisoners, and an international relief agency. It also endorses chaplains to the military.