Lanagan is a city in McDonald County, Missouri, in the United States. It is near Truitt's Cave. The population was 411 at the 2000 census, at which time it was a town. It is part of the Fayetteville–Springdale–Rogers, AR-MO Metropolitan Statistical Area.
Lanagan is located at 36°36′26″N 94°26′59″W / 36.60722°N 94.44972°W / 36.60722; -94.44972 (36.607270, -94.449612).
According to the United States Census Bureau, the town has a total area of 1.0 square miles (2.5 km²), all land.