denomination organized in 1918 by uniting the Lutheran and Reformed churches in Bohemia and Moravia (now Czech Republic). Subsequently, other smaller Czech Protestant groups merged into this church. Its roots go back to the 16th-century Protestant Reformation and to the 15th-century Hussite movement in Bohemia, which was made up of the followers of the reformer Jan Hus. His followers were crushed in 1434, but the movement persisted underground. During the 16th-century Reformation, the Hussites emerged again and flourished for a brief period, but in 1547 they were again suppressed. Lutheran and Reformed groups also made progress in the country until the Czech Protestants' unsuccessful revolt against the Habsburgs in 1618, following which thousands of them fled the country and many of their leaders were executed. Protestants in Bohemia did not regain religious rights until 1781 when Joseph II, the Holy Roman emperor, issued his Edict of Toleration.

The new country of Czechoslovakia was created in 1918 by merging Bohemia, Moravia, Slovakia, and Ruthenia. The Evangelical Church of Czech Brethren quickly became the leading Protestant church in the nation. It was a leader in the fields of theological education and social work. The church and the nation again suffered severely during World War II under Nazi rule. When the Communists gained control of the government in 1948, the Evangelical Church of Czech Brethren tried to work with them, but the church suffered severe repression under the government from 1969 until the fall of the Communist regime in 1989–90.