in ancient Rome corporations of persons united by the performance of religious rites or by practice of a common profession.

Collegia were of various types, including religious, priestly (such as the Arval Brethren, Pontifices, Augures, Fetiales, and Salii), trade, veteran, and funeral collegia. The head of a collegia was an elected magister. Every five years the list of members of the collegia was revised. The collegia had common sacred objects, a common treasury, and common places for religious rites, for assemblies, and for meals; they also had patrons from the upper classes. From the first century B.C.., the collegia, and particularly the trade collegia and neighborhood collegia, uniting freedmen and slaves interfered in political life; this led to their periodic ban (for example, after the First Catilinarian Conspiracy in 66 B.C.). In the era of the Roman Empire the collegia functioned only with government authorization. In addition to the traditional collegia, new ones were founded such as Augustales, in charge of the cult of the emperor, and domestic cults, which consisted of slaves who venerated the attendant spirit (genius) of their master. During the period of the late empire, membership in most of the trade collegia became compulsory.

(Russian,kollegii), in Russia in the 18th century, central institutions in charge of individual branches of government administration.

Collegia were introduced by Peter I to replace the prikazy (offices); by establishing them, Peter hoped to centralize administration and make a clear-cut differentiation of functions between the departments. From 1717 to 1721 the staff and presidents of 12 collegia were appointed: Foreign Affairs, the Army, the Navy, State Revenues, State Expenses, Audit, Justice, Mining, Manufacturing, Commerce, Votchiny (Patrimonial Estates), and the Main Office for Municipal Administration. In 1718–20 the functions of each collegia were defined, the structure and the staff approved, and general rules of procedure established (1720). Each collegia consisted of an executive staff (president, vice-president, four counsellors, four assessors, and a secretary) and a staff of officials and office workers. The collegia were subordinated to the emperor and the Senate. Each collegia had a treasurer (later a state attorney), who audited the collegium. Some collegiums had local agencies.

In 1722–27 and in 1764–86 the Collegium of Little Russia was set up as the administrative body for the Ukraine. In 1726 the Collegia of the Economy was created. Around 1725 the Juridical Collegia for the Affairs of Lithuania, Estonia, and Finland (Iustits-Kollegiia Lifliandskikh, Estliandskikh, i Finliandskikh Del) was established; in 1736 this became the Chamber Office for the Affairs of Lithuania, Estonia, and Finland. Under the successors of Peter I, the Manufacturing and the Mining collegia were temporarily suspended. In 1763 the Medical Collegia was created.

The provincial reform of 1775 created a network of local institutions that took over many of the functions of the collegia. As a result the State Expenses, Audit, State Revenues, and Justice collegia and the Collegium of the Economy were abolished in the 1780’s. The remaining collegia existed until the early 19th century, when their functions were assumed by the newly established ministries.