A collegium (plural collegia, "joined by law") may be:
- collegium (ancient Rome), a term applied to any association with a legal personality in ancient Rome.
- a Latinized form of the Ancient Greek term hetaireia.
- Collegium Musicum, any of the university-oriented music societies of Reformation-era Germany and Switzerland; today, a common name for (usually early-) music ensembles, mostly at universities
- an executive body of the central government in the Imperial Russia.
- a collegial advisory and controlling body at a Soviet ministry, state committee or agency.
- Collegium (school), in France, refers to a kind of college.
- In Scandinavia, an outdated spelling of kollegium and refers to dormitories, e.g.
- Harvard-Radcliffe Collegium Musicum
Also, the word college is derived from collegium.