The congregation became self-supported and was no longer on mission church status.

Trinity’s attribute as a giving congregation became apparent during the World War 1 years when the church contributed to overseas relief and donated Bibles to men in the armed service. Following the conflict the Women’s Missionary Society pledged money for post-war reconstruction in Europe. A highlight in Lutheran church history during this period was the merger of a number of Lutheran church bodies to form the United Lutheran Church in America, an important step toward further church union. Trinity Lutheran was a mission church until April 1921 when it became self-supporting. A period of economic and population growth in Long Beach, triggered largely by discovery of oil on Signal Hill in 1920, brought many Lutherans from the Midwest to California. Church membership grew steadily, and more complete facilities were essential to accommodate the Sunday School and other educational programs. In May 1928 a beautiful Gothic edifice replaced the original “little brown church.” The total cost of the new structure, included furniture and furnishings, was $17,407.76. Ferman H. Thresh, a deacon of the church, oversaw the construction of the new building.