The parish consists of 3,271 acres in the administrative area of Mid Suffolk District Council and is one of the five parishes which comprise Thredling Hundred. An extensive plateau of 200 feet is penetrated in the Debenham area by the shallow valleys of four streams which unite to form the River Deben that meets the sea at Felixstowe. The soil, apart from near the streams, is a heavy moisture retaining clay overlying chalk.

The population in 1801 was 1,215 and one hundred years later in 1901 had reduced to 1,182. The population in 1998 was estimated to be about 2,252 in about 850 households. There are currently 1,519 people on the electoral roll but this excludes people under 18.

The Debenham Parish Council meets every second and third Monday of the month (except during August) at 7.30pm in Dove Cottage next to the Church in the High Street. The public may attend these meetings and may ask questions during the 10 minute public sessions that are scheduled close to the beginning and end of each Parish Council Meeting.

There is an Annual Parish Meeting when the public are allowed to participate. Elections are held every four years, the last being in May 2007. Any householder may put him/herself up for election at that time, or during a term when vacancies occur.

The Parish Council is allowed by law to provide public conveniences and can prosecute noise makers or litter bugs. It maintains the allotments and St Mary’s Churchyard and clock, the cemetery and the play areas. It has the right to be notified of any planning application affecting the area and to make comments to the planning authority. It assists Suffolk County Council in the maintenance of public footpaths and bridleways and undertakes the maintenance and provision of street lighting.

The Parish Council reviews and sets a budget annually which is levied through the District Council. The intermediate council between the Parish and County Councils is the Mid Suffolk District Council.