Vassar is a census-designated place (CDP) in Osage County, Kansas, United States.

A post office was opened in La Mont's Hill (an extinct town) in 1871, but it was moved to Vassar in 1887.

[4] The Missouri Pacific Railroad previously went through Vassar,[5] but it was abandoned, then later it was converted into the Flint Hills Nature Trail.

The climate in this area is characterized by hot, humid summers and generally mild to cool winters.

This article about a location in Osage County, Kansas is a stub.