Alarilla is a municipality in the province of Guadalajara, within the autonomous community of Castile-La Mancha, Spain. It is a small rural settlement in the central part of the country, located in the region historically known as the Alcarria.
The municipality is sparsely populated. According to the 2004 census conducted by Spain's National Statistics Institute (INE), Alarilla had a population of 122 inhabitants. This figure reflects the pattern of small, low-density municipalities characteristic of the province of Guadalajara.
As a municipality, Alarilla constitutes a basic unit of local administration in Spain, encompassing the settlement and its surrounding territory within the Guadalajara province.