Geroldswil is a municipality in the district of Dietikon in the canton of Zürich in Switzerland, located in the Limmat Valley.

Of the rest of the land, 42.9% is settled (buildings or roads) and the remainder (5.8%) is non-productive (rivers, glaciers or mountains).

As of 2007[update] 43.8% of the total municipal area was undergoing some type of construction.

[5] Originally a linear village (Strassendorf) in the Limmattal, in the second half of the 20th century, Geroldswil has grown into a suburban extension of the agglomeration of Zürich.

Most of the population (as of 2000[update]) speaks German (89.8%), with Italian being second most common ( 2.9%) and Serbo-Croatian being third ( 0.9%).

In the 2007 election the most popular party was the SVP which received 44.3% of the vote.