Play-Doh, also known as Play-Dough, is a modeling compound for young children to make arts and crafts projects. The product was first manufactured in Cincinnati, Ohio, United States, as a wallpaper cleaner in the 1930s. Play-Doh was then reworked and marketed to Cincinnati schools in the mid-1950s. Play-Doh was demonstrated at an educational convention in 1956 and prominent department stores opened retail accounts.

Advertisements promoting Play-Doh on influential children's television shows in 1957 furthered the product's sales. Since its launch on the toy market in the mid-1950s, Play-Doh has generated a considerable amount of ancillary merchandise such as the Fun Factory.

The non-toxic, non-staining, reusable modeling compound that came to be known as "Play-Doh" was a pliable, putty-like substance concocted by Noah McVicker of Cincinnati-based soap manufacturer Kutol Products. It was devised at the request of Kroger Grocery, which wanted a product that could clean coal residue from wallpaper.

Following World War II, the demand for wallpaper cleaning putty shrank substantially. The increasing popularity of natural gas in heating applications and corresponding reduction of coal use resulted in a decrease of indoor soot build-up in homes and businesses. The introduction of washable vinyl-based wallpaper further rendered many such specialized cleaning products unnecessary. McVicker's nephew, Joe McVicker, joined Kutol with the remit to save the company from bankruptcy. Joe McVicker was the brother-in-law of nursery school teacher Kay Zufall, who had seen a newspaper article about making art projects with the wallpaper cleaning putty. Her students enjoyed it, and she persuaded Noah McVicker (who also sold the putty) and Joe McVicker to manufacture it as a child’s toy. Zufall and her husband came up with the name Play-Doh; Joe McVicker and his uncle Noah had wanted to call it "Rainbow Modeling Compound".

Joe McVicker took Play-Doh to an educational convention for manufacturers of school supplies, and Woodward & Lothrop, a department store in Washington, DC began selling the compound. In 1956, the McVickers formed the Rainbow Crafts Company to make and sell Play-Doh. Also in 1956, a three-pack of 7-ounce cans was added to the product line, and, after in-store demonstrations, Macy's of New York and Marshall Field's of Chicago opened retail accounts. In 1957, chemist Dr. Tien Liu reduced Play-Doh's salt content (thus allowing models to dry without losing their color), and Play-Doh ads were telecast on Captain Kangaroo, Ding Dong School, and Romper Room. In 1958, Play-Doh's sales reached nearly $3 million. ($33.6 million as of November 2025)

In 1964, Play-Doh was exported to Britain, France, and Italy. By 1965, Rainbow Crafts received a patent for Play-Doh. Also in 1965, the food company General Mills bought Rainbow Crafts for $3 million. In 1967, General Mills bought Kenner Products. In 1971, Rainbow Crafts and Kenner merged, and, in 1987, the Tonka Corporation bought the two. In the 1980s, its cardboard can (with a rust-prone metal bottom) was replaced with a more cost effective plastic container. In 1991, Hasbro became the owner of Play-Doh, putting the compound under its Playskool brand, and continues to manufacture the product today. In 1996, gold and silver were added to Play-Doh's palette to celebrate its 40th anniversary.

More than two billion cans of Play-Doh were sold between 1955 and 2005, and, in 2005, Play-Doh was being sold in 75 countries at 95 million cans a year. In the United States, more than 6,000 stores carry Play-Doh.

Play-Doh was inducted into the National Toy Hall of Fame at The Strong in Rochester, New York, in 1998.