The Gustav-Adolf-Werk (GAW) is a society under the roof of the Evangelical Church in Germany (EKD) which has for its object the aid of feeble sister churches and congregations. It is responsible for the taking care of the diaspora work of the EKD, in cooperation with the EKD itself, its member churches and congregations. The organization started with a focus on the diaspora, but has separate branches internationally in the meanwhile. The organization in Austria is still called the Gustav-Adolf-Verein, which was the original name in Germany as well. Further terms used for the GAW in the past include Gustavus Adolphus Union, Gustav-Adolf-Stiftung and Evangelischer Verein der Gustav-Adolf-Stiftung.

The Protestant Church in Germany, formerly known in English as the Evangelical Church in Germany, is a federation of twenty Lutheran, Reformed, and United Protestant regional Churches in Germany, collectively encompassing the vast majority of the country's Protestants. In 2022, the EKD had a membership of 19,153,000 members, or 22.7% of the German population. It constitutes one of the largest Protestant bodies in the world. Church offices managing the federation are located in Herrenhausen, Hanover, Lower Saxony. Many of its members consider themselves Lutherans.