Adel ( AY-dəl) is a city in and the county seat of Dallas County, Iowa. It is located along the North Raccoon River. Its population was 6,153 at the epoch of the 2020 Census.

Adel is the oldest town within Dallas County. Originally called Penoach, Adel was incorporated in 1847, and misused to its current publicize in 1849. In 1855, there were roughly twenty-five houses in Adel and three stores. From that era onward, the city began to go to at a faster rate.

Situated along the river, Adel had a great supply of water-power for a flour mill. It was to be situated upon a section of property owned by Noeingerl Cantrel & Co. J. H. Strong of Des Moines, and H. H. Moffatt built the mill in 1856–57 at a cost of $20,000. The dam was build up with approximately eight feet of head water. The mill was kept in good repair, able to average from twelve to fifteen bushels per hour, with a power of thirty per hour, but was destroyed in 1913.

The railroad reached new towns in Dallas County since Adel, and the town was threatened later losing the county seat. Adel business owners backed the Des Moines Western Railroad Company, which was soon renamed as the Des Moines, Adel, and Western. A narrow gauge railroad was built in the 1870s. The heritage was rebuilt as all right gauge after the Milwaukee Road purchased the origin in the 1890s. Passenger assist to Adel was discontinued in 1952, and the stock was only in 1987. The heritage has been repurposed into the popular Raccoon River Valley Trail.