Carl Olof Rosenius was a Swedish lay preacher, author and editor of the monthly Pietisten from 1842 to 1868. He was one of the country's most widely-heard preachers of his day and has been described as being of "extraordinary importance for the low-church evangelical revival not only in Sweden but also in the other Nordic countries".

Läsare or the Reader movement was a Swedish Pietistic Christian revival movement of people who stressed the importance of reading, that is, reading the Bible and other Christian literature. It was influenced by both the Herrnhuters and the Methodists and has been described by scholar George M. Stephenson as a "second religious reformation in Sweden".