Ammerswil is a municipality in the district of Lenzburg in the canton of Aargau in Switzerland.

While some scattered Neolithic items have been discovered in Ammerswil, the first known settlement was an Alamannic farmhouse.

[3] It was ruled successively by the Counts of Lenzburg, Kyburg and Habsburg, and then in 1415 by the city-state of Bern.

Starting in the 13th century, the rights to low justice and tithes were held by the Lords of Hallwyl.

[3] Ammerswil has an area, as of 2009[update], of 3.19 square kilometers (1.23 sq mi).

The blazon of the municipal coat of arms is Argent a Semi Deer rampant issuant Gules from Coupeaux Vert.

[8] The age distribution, as of 2008[update], in Ammerswil is; 65 children or 9.9% of the population are between 0 and 9 years old and 87 teenagers or 13.2% are between 10 and 19.

[10] About 65.6% of the total households were owner occupied, or in other words did not pay rent (though they may have a mortgage or a rent-to-own agreement).

[12] The historical population is given in the following table:[3] The Pfrundspeicher (Prebendary store house) on Hendschikerstrasse is listed as a Swiss heritage site of national significance.

[8] From the 2000 census[update], 161 or 26.4% were Roman Catholic, while 363 or 59.6% belonged to the Swiss Reformed Church.