The collection consists of records of the bishop's administration, and of his officials. The bishops' registers, which at first contained all episcopal acts but later recorded only certain important items of business, start with Bishop Montacute's register in 1337. Earlier registers, and those from 1610 to 1702, are lost, but transcripts of some 17th century registers survive.

From the fifteenth century separate registers and records were kept of various branches of the bishop's administration. Visitation records, periodic inquiries into the state of the diocese, personnel, fabric, endowments and social conditions, survive from the mid sixteenth century. They include returns to visitation inquiries from 1775, and churchwardens' presentments of abuse and things amiss in parishes from 1582.

Much of the bishop's business was transacted through his consistory court. The records include actual law-suits which took place in the court, either office cases where the diocese was prosecutor (early sixteenth century onwards), or instance cases, between two private parties (mostly seventeenth century). Until 1856 the bishop (and in some Cambridgeshire parishes the archdeacon) had the probate of wills. The registers and surviving wills, long separated from the diocesan records, are now deposited at Cambridgeshire County Record Office. The diocesan records still include registers of administration of those who died intestate (late sixteenth century onwards). Other records stemming from consistory court include marriage licences (intermittent from 1711, continuous from 1742), ordination papers (from 1771), curates' licences (from 1816; earlier licences in general registers), licences for non-residence of incumbents (from 1812), consecrations of new churches (from 1834), and faculties for alterations to churches (registers from 1724, papers mostly post-1870).

Government required certain records to be kept, notably annual transcripts from parish registers (1599-c.1860), registration of dissenting meeting houses (1697-1852), mortgages of benefices to pay for rebuilding of parsonages (from 1790), and tithe maps and apportionments (c.1840) (Huntingdonshire maps at Huntingdon County Record Office).

The bishops had extensive manorial and other estates and endowments. These were first surveyed and recorded in the Old Coucher book, 1251. For some manors there are long runs of medieval court rolls and bailiff's accounts. In the mid nineteenth century the episcopal estates were commuted to the Ecclesiastical Commissioners (now the Church Commissioners [CC]), and the Commissioners took over a large quantity of post-medieval court books and leases. These have now been returned to the Library and stand alongside the diocesan records.

The bishop's temporal jurisdiction over the Isle of Ely was abolished in 1836. Until then the bishop's officials held assizes and quarter sessions. Records of these courts survive for the seventeenth and eighteenth centuries.