The gendarmerie founded in 1911, and since World War II it complete reorganized and reevaluation reformed, and by the 1970s it developed into a vast, professional rural police force. Originally set up under the Ministry of Finance to control rural banditry so that taxes could be coaxed in the lawless countryside, the gendarmerie was organized and commanded by Swedish officers in its formative years. When Reza Shah was crowned in 1926, he absorbed the gendarmerie into the army in an effort to consolidate central government authority. This organization remained unchanged until 1943, after the abdication of Reza Shah in favor of his son, when the gendarmerie was given organizational autonomy under the Ministry of Interior. It retained this autonomy in 1977.

Of considerable assistance in the reform efforts has been the United States Military Mission to the Imperial Iranian Gendarmerie (known as GENMISH), which organized in 1953 and was terminated in 1976. Consisting of approximately twenty United States military officers and ten civilians, GENMISH assisted in the gendarmerie's reorganization and gave advice on organizational and training matters.

By the 1970s the missions of gendarmerie included, in addition to routine rural police functions, the apprehension of smugglers of narcotics and other contraband, the maintenance of internal security and border security, traffic control of highways, and acting as an adjunct to the army in time of war or national emergency. Since 1972 the gendarmerie had also been placed in charge of the National Resistance Force, a widespread though largely inactive, militia organization charged with training citizens in the defense of their homes and villages. In a more abstract sense perhaps the most important function of the gendarmerie was its role as the manifestation of central government authority to much of the Iranians population. In a country with such a disparate population whose allegiances have historically been directed toward local authorities, the importance of this function can scarcely be overemphasized. Personnel of gendarmerie posts (of which there were over 2,000 in the 1970s) routinely were patrol their assigned areas, serving government notices, settle disputes, and exchanged news in addition to providing police protection. In this way, and in their capacity as highway patrolmen, the gendarmes could keep aware of any unusual incidents and the passage of strangers. In short a key gendarmerie function was to gather intelligence in the vast, sparsely populated regions of the country.

In the mid-1970s gendarmes had a fairly wide range of modern equipment, including light aircraft, large Huey and small helicopters, some forty patrol boats, armored patrol cars and jeeps, trucks, and motorcycles. Most of this equipment had been recently acquired, and the improvement in the mobility of the gendarmerie has been accompanied by the installation of a nationwide radio network linking all posts.

The gendarmerie used the same basic uniform as the army, had the same rank structure, and patterned its organizational structure after that of the armed forces. The largest gendarmerie unit was the district, of which there were fourteen in 1975. Districts, in turn, were divided into two or more regiments, each headquarters in a provincial town. About a third of the districts operated at brigade strength. Each regiment controled about six companies, whose command posts were located in smaller municipalities. Finally company areas were apportioned among posts located in villages, at road junctions, and in strategic rural areas which were the basic gendarmerie unit. Gendarmerie posts were of squad size and were usually under the command of an officer and two or more noncommissioned officers. Central headquarters was located in Tehran. In addition to its stationary units, The gendarmerie was contained numerous mobile units that were able to carry out sustained pursuit of hostile persons or groups.