The rights to low justice were held by the Lords of Rinach and Hallwyl before they went into the possession of Bern, as part of the court district of Trostberg.

The tithes, originally collected by Säckingen Abbey, later went to the Lords of Hallwyl who then gave them as a gift to the church of Seengen.

In 1528 Bern converted to the Protestant Reformation and Hallwil became part of the Seengen parish.

In the 18th century, the straw plaiting, silk ribbon and linen weaving industries became important.

At the end of the 20th century small companies in the service sector and apparatus dominated.

[3] Hallwil is located in the Lenzburg district, on the left side of the Seetal valley.

[4] The blazon of the municipal coat of arms is Gules a Palm tree Vert fructed Or issuant from Coupeaux of the second.

[8] The age distribution, as of 2008[update], in Hallwil is; 65 children or 8.8% of the population are between 0 and 9 years old and 81 teenagers or 10.9% are between 10 and 19.

[10] About 51% 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).

[8] The historical population is given in the following table:[3] The municipality has several midwinter-festivals or customs that were once celebrated throughout the Seetal, but now mostly only happen in Hallwil.

[15] The Wienechtschind occurs on December 24 and consists of 7 girls (Christmas children) who travel throughout the town singing at each house.

Silvestertrösche occurs on New Year's Eve when a large Silvester bonfire is lit on a hill near Hallwil.