Lengwil is a municipality in the district of Kreuzlingen in the canton of Thurgau in Switzerland.

The municipality was created in 1998 by a merger of the Ortsgemeinde of Illighausen and the village of Oberhofen bei Kreuzlingen.

[3] During the merger, the village of Schönenbaumgarten (which had been part of Illighausen) went to the municipality of Langrickenbach.

With the Protestant Reformation most of the village converted to the new faith and became a separate parish.

The local economy revolved around agriculture until the 19th century when dairy farming was added.

However, limited road access to the village as prevented any industries from settling in Illighausen.

[5] Oberhofen is first mentioned in 1160, but was settled earlier, as several Early Middle Ages graves indicate.

Dettighofen, Lengwil and Oberhofen formed a lower court for the Herrschaft of Liebburg.

The village chapel was first mentioned in 1477 and was a curacy of the Monastery of St. Stephen in Constance.

In the 16th century the chapel was supervised by the parish of Altnau, followed by Güttingen between 1620 and 1712 and after 1712 by Scherzingen.

[6] Lengwil has an area, as of 2009[update], of 8.89 square kilometers (3.43 sq mi).

It consists of the former municipalities of Illighausen and Oberhofen, the villages of Dettighofen and Lengwil and the hamlet of Ast.

Most of the population (as of 2000[update]) speaks German (96.1%), with Italian being second most common (0.9%) and English being third (0.6%).

[9] The age distribution, as of 2009[update], in Lengwil is; 156 children or 11.4% of the population are between 0 and 9 years old and 178 teenagers or 13.0% are between 10 and 19.

[10] From the 2000 census[update], 335 or 27.3% were Roman Catholic, while 663 or 54.0% belonged to the Swiss Reformed Church.

Of the children in kindergarten, 11 or 42.3% were female, 4 or 15.4% were not Swiss citizens and 3 or 11.5% did not speak German natively.

At the lower primary level, there were 17 children or 63.0% of the total population who were female, 1 or 3.7% were not Swiss citizens and 2 or 7.4% did not speak German natively.

In the upper primary level, there were 15 or 60.0% who were female, 2 or 8.0% were not Swiss citizens and 2 or 8.0% did not speak German natively.