The Oakdale Affair is a short contemporary mystery novel by Edgar Rice Burroughs. It was written in 1917 under the working title of "Bridge and the Oskaloosa Kid," and is a partial sequel to The Mucker (1914/1916), Bridge, the protagonist, having been a secondary character in the earlier work. It was first published in Blue Book Magazine in March 1918. Its first book publication paired it with an unrelated tale, "The Rider," in The Oakdale Affair and The Rider, issued by Edgar Rice Burroughs, Inc. in February 1937 and subsequently reprinted by Grosset & Dunlap in 1937, 1938 and 1940. The story's first independent book publication was in a paperback edition from Ace Books in July 1974. Subsequent hardcover editions were issued by Buccaneer (1977) and Ameron; a subsequent paperback edition was issued by Charter (1979). Most editions omit the original ending, consisting of the last 174 lines of the magazine version, though the Buccaneer and Charter editions restore it.

In the home of Jonas Prim, president of an Oakdale bank, a thief makes off with a servant's clothing and valuables belonging to Prim's daughter Abigail. Abigail is thought to be absent visiting Sam Benham, whom her parents want her to marry. Escaping, the thief later encounters a group of hobos and is taken for one of them, the Oskaloosa Kid. Two of the hobos attempt to murder the newcomer for the loot, who shoots at one and flees.

Meanwhile, the Prims discover the theft and learn that Abigail never arrived at Benham's. The incidents are assumed to be connected to other crimes, the assault and robbery of John Baggs and the murder of Reginald Paynter, who had been seen with two men and a girl. The local paper speculates Abigail might have been involved with Paynter's murder. Mr. Prim hires a private eye.