It is located in the province of Western Finland and is part of the Southern Ostrobothnia region. The municipality has a population of 14,002 (2003) and covers an area of 750.92 kmē of which 13.61 kmē is water. The population density is 18.6 inhabitants per kmē.
The municipality is unilingually Finnish.
Lapua is famous for the anti-communist Lapuanliike .