The New Zealand police service is moulded to the British pattern, except for its national organisation with central headquarters control. In Britain the service is divided into autonomous Constabularies.

A military officer, first, Major Gudgeon (1887–90) and then Lieutenant Colonel A. Hume (1890–97), remained in charge of the Police Force until the first Police Commissioner, J. B. Tunbridge (1898–1903), was appointed. He was an experienced officer from England and had also served for several years in the Armed Constabulary. The system of appointing the Commissioner from the ranks continued from this time, and the principle that “every constable potentially carries the Commissioner's baton” is highly valued.

In 1958 a new Police Act was passed in which the word “Force” was discarded, and now the proper title is “The New Zealand Police”. Today the New Zealand Police is a Government Department, though it is recruited, organised, and governed somewhat differently from others. It is established by an Act of Parliament and is under the control of a Cabinet minister who is responsible for policy and overall administration. But direct control is the responsibility of a Commissioner.

For organisational purposes New Zealand is divided into 15 districts, each being under the control of a commissioned officer who has the responsibility for law and order in his area. Each district has a central station, from which are controlled subsidiary and suburban stations. Altogether there are 352 police stations.

The first Police Training School was opened at Mount Cook, Wellington, in 1898. Training continued to be given in the Wellington area until 1953, when a training school was opened in Lyttelton. In 1955, when a rapid expansion of the Police was decided upon, a new centre was established at Trentham, near Wellington. This school not only trains recruits and cadets but also provides short courses for sergeants, senior sergeants, detectives, and commissioned officers. The barracks, with sleeping accommodation for 180, are normally full. Facilities include recreation rooms, canteen, library, gymnasium, and assembly hall. Nearby are playing fields, rifle ranges, and swimming baths.

To join the New Zealand Police an applicant must meet certain standards. He must be at least 19 years of age (17 in the case of a cadet) and not more than 35 and be at least 5 ft 8½ in. tall, well built, in first-class health, and of good eyesight and hearing. He must produce references to character and show he has not been convicted of any criminal offence. He must pass an educational test. The recruit then undergoes a 13-week training course at Trentham; for cadets it is 19 months. Training is not complete at the end of this period. For the next 21 months the recruit, posted to a station, takes an in-service training course in law. When this is completed he sits an examination for permanent employment.