The Lemmensinstituut is a Belgian conservatory of music. It was founded in Mechelen, in 1879, by the Belgian bishops as the Ecole de musique religieuse. It was later renamed after its first director, Jacques-Nicolas Lemmens.
Although its programs were greatly expanded over the years, it remained in essence a school of religious music until the 1960s and 1970s, when major changes occurred. It moved to Leuven in 1968, and its programs were aligned on those of Belgium's conservatories of music, such that in 1971 its "laureate" diploma was considered legally equivalent to a "First Prize" of a conservatory. It also added a teacher's training course, and a high school specializing in music.