Boquerón is a department in the western region of Paraguay. It is the country's largest department, with an area of , but its population is only 45,617 (2002 census). The department includes the Russian Mennonite colonies of Fernheim, Menno and its administrative center Loma Plata and Neuland. The capital is Filadelfia. Other towns are General Eugenio A. Garay, Doctor Pedro P. Peña and Mariscal Estigarribia.
The western region—Paraguay Occidental—with two percent of the Paraguayan population, produces nearly 65% of the country's milk and meat. High agricultural output is linked to the advanced technology and industry of the Mennonite settlements.
In 1945 Boquerón was split, with the portion separated off being renamed "Nueva Asunción". The reduced remaining area continued to be called "Boquerón", and the Department's capital was moved to Filadelfia (the previous capital had been Doctor Pedro P. Peña). However, in 1992 the previous department Nueva Asunción was re-integrated into Boquerón, effectively re-forming the Department as of 1945 when it was split, except that after 1992 the enlarged department's capital remained at Filadelfia.