Konventikelplakatet (The Conventicle Act) was a Swedish law, in effect between 21 January 1726 and 26 October 1858. The act outlawed all conventicles, or religious meetings of any kind, outside of the Swedish Lutheran Church, with the exception of the family prayer or worship. The purpose was to prevent freedom of religion and protect religious unity, as such unity was regarded as important to maintain the control of the crown over the public through the church.
The law was initiated in 1726 to prevent the popularity of pietism, which was spreading rapidly in Sweden in the first half of the 18th century. During the 19th century, it was used as a tool against the spread of the free churches.
This law was one reason for the large emigration from Sweden to the USA in the 1840s and 1850s. During the 19th century, the law had become controversial and was constantly debated in parliament. After several years of debate, it was finally abolished in 1858. The new law stipulated that conventicles were not to take place in parallel with the services of the Lutheran Church without prior dispensation. This condition was abolished in 1868 and replaced with the condition that such gatherings were not to take place in the close surroundings of a Lutheran church.
The Conventicle Act was also in effect in Finland from 1726, as Finland was at the time a Swedish province. In Finland, the act was abolished 1 July 1870.