Beg to Differ is the second studio album by American heavy metal band Prong, released in 1990 through Epic Records. The album includes one live track ("Third from the Sun", a Chrome cover) recorded at CBGB's in New York City in 1989. Brian "Pushead" Schroeder did the design and cover artwork for the album. Part of the song "Lost and Found" was used for commercial breaks of MTV's Headbangers Ball in the early 1990s.

Beg to Differ was the start of Prong's change in music direction, showcasing an experimentation with thrash and speed arrangements and hardcore influences inspired by the likes of Bad Brains and Suicidal Tendencies. The album also stands as one of the earliest examples of the then-emerging subgenre of groove metal, predating Pantera's Cowboys from Hell by four months; this fact was later acknowledged by Prong vocalist and guitarist Tommy Victor, who claimed, "[Beg to Differ] was the first groove metal record. It gets overlooked, but I don't know who came out with anything before that."