- Hymns, Ethiopic1
- Hypothesis1
- Ibn al-Nafīs, ʻAlī ibn Abī al-Ḥazm, 1210 or 1211-1288. Mūjiz1
- Iceland1
- Ildephonsus, Saint, approximately 610-6671
- Ildobrandini, Geronimo1
- Illumination of books and manuscripts, Flemish1
- Illumination of books and manuscripts, French1
- Illumination of books and manuscripts, Gothic1
- Illumination of books and manuscripts, Medieval1
- Illumination of books and manuscripts, Renaissance1
- Illumination of books and manuscripts--Technique1
- Impediments to marriage1
- In Coena Domini bulls1
- India1
- Indians, Treatment of1
- Indulgences (Canon law)1
- Influence (Literary, artistic, etc.)1
- Inheritance and succession (Canon law)1
- Inheritance and succession (Roman law)1