- Indians, Treatment of1
- Indulgences (Canon law)1
- Influence (Literary, artistic, etc.)1
- Inheritance and succession (Canon law)1
- Inheritance and succession (Roman law)1
- Inner Light1
- Innocent III, Pope, 1160 or 1161-12161
- Innocent IV, Pope, approximately 1200-12541
- Innocent V, Pope, approximately 1224-12761
- Innocent VIII, Pope, 1432-14921
- Inscriptions, Latin1
- Inspiration1
- Institutiones oratoriae (Quintilian)1
- Intellectual life1
- Interdict (Canon law)1
- Introductions1
- Investiture1
- Investiture (Feudal law)1
- Ireland1
- Isabella I, Queen of Spain, 1451-15041