Protestantism was introduced in Bulgaria by missionaries from the United States in 1857-58, amid the National Revival period. The two main denominations, the Methodists and Congregationalists, divided their areas of influence. The former predominated in northern Bulgaria and the latter in the south. In 1875 the Protestant denominations united in the Bulgarian Evangelical Philanthropic Society, which later became the Union of Evangelical Churches in Bulgaria. Besides setting up churches, the Protestants established schools, clinics, and youth clubs, and they distributed copies of the Bible and their own religious publications in Bulgarian. The Union of Evangelical Churches produced the first translation of the entire Bible into Bulgarian in 1871 and founded the nondenominational Robert College in Constantinople, where many Bulgarian leaders of the post-independence era were educated. After independence in 1878, the Protestants gained influence because they used the vernacular in services and in religious literature.

The communist regimes subjected Protestants to even greater persecution than the Catholics. In 1946 church funding was cut off by a law curbing foreign currency transactions. Because many ministers had been educated in the West before World War II, they were suspected automatically of supporting the opposition parties. In 1949 thirty-one Protestant clergymen were charged with working for American intelligence and running a spy ring in Bulgaria. All church property was confiscated, and the churches' legal status was revoked. Most of the mainstream Protestant denominations maintained the right to worship nominally guaranteed by the constitution of 1947.

According to estimates in 1991, the 5,000 to 6,000 Bulgarian Pentecostals made that sect the largest Protestant group (see table 7, Appendix). The Pentecostal movement was brought to Bulgaria in 1921 by Russian émigrés. The movement later spread to Varna, Sliven, Sofia, and Pleven. It gained popularity in Bulgaria after freedom of religion was declared in 1944, and the fall of Zhivkov brought another surge of interest. In 1991 the Pentecostal Church had thirty-six clergy in forty-three parishes, with sufficient concentration in Ruse to petition the government to establish a Bible institute there.

In 1991 the Adventist Church had 3,500 Bulgarian members, twothirds of them young people. The Adventist movement began in the Dobruja region of Bulgaria at the turn of the century and then spread to Tutrakan, Ruse, Sofia, and Plovdiv. It gained momentum in Bulgaria after 1944. Under the communist regimes, mainstream Adventists maintained the right to worship. Some twenty parishes with forty pastors remained active through that era, although a breakaway reformed group was banned because of its pacifist beliefs. Some Adventists were imprisoned for refusal of military service.

Data as of June 1992