- Little office of the Immaculate Conception2
- Liturgical books10
- Liturgics298
- Liturgies6
- Manuscript waste14
- Manuscripts21
- Manuscripts, Ethiopic1
- Manuscripts, Latin12
- Manuscripts, Latin (Medieval and modern)48
- Manuscripts, Latin--15th century1
- Manuscripts, Medieval29
- Manuscripts, Renaissance5
- Mary, Blessed Virgin, Saint, in the liturgy1
- Maurice, Saint, -approximately 2871
- Mensural notation7
- Michael (Archangel)1
- Michaelmas1
- Michigan--Kalamazoo1
- Missing leaves2
- Missouri--Saint Louis14