Gloucestershire ( (listen) abbreviated Glos) is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn and the entire Forest of Dean.

The county town is the city of Gloucester and other principal towns and villages include Cheltenham, Cirencester, Kingswood, Bradley Stoke, Stroud, Thornbury, Yate, Tewkesbury, Bishop's Cleeve, Churchdown, Brockworth, Winchcombe, Dursley, Cam, Berkeley, Wotton-under-Edge, Tetbury, Moreton-in-Marsh, Fairford, Lechlade, Northleach, Stow-on-the-Wold, Chipping Campden, Bourton-on-the-Water, Stonehouse, Nailsworth, Minchinhampton, Painswick, Winterbourne, Frampton Cotterell, Coleford, Cinderford, Lydney and Rodborough and Cainscross that are within Stroud's urban area.

Gloucestershire borders Herefordshire to the north-west, Worcestershire to the north, Warwickshire to the north-east, Oxfordshire to the east, Wiltshire to the south, Bristol and Somerset to the south-west, and the Welsh county of Monmouthshire to the west.

The current Gloucestershire County Council area does not have the same geographical boundaries as the historic county. Some northern parts of the county, including Long Marston and Welford-on-Avon, were transferred to Warwickshire in 1931. Following the Local Government Act 1972, some southern parts of the county were transferred for administrative purposes to the new county of Avon, which ceased to exist on 1 April 1996. After 1996, the city of Bristol and South Gloucestershire became separate unitary authorities.