Knock Knock is Smog's seventh album, released in 1999. Following Red Apple Falls, his first collaboration with Jim O'Rourke as a producer, Knock Knock elaborates O'Rourke's sound and provides twists and edges to the folky style of its predecessor. Held was the first single, followed by Cold Blooded Old Times, which was also featured on the High Fidelity-soundtrack, thereby gaining some attention to Callahan's work. Other soundtrack-appearances include Teenage Spaceship in Crazy (2000, directed by Hans-Christian Schmid) and River Guard in Swimming (2000, directed by Robert J. Siegel). The album was accompanied by the release of the single Look Now, featuring the two Japanese bonus tracks. 　　Loren Mazzacane Connors plays guitar on this album, Tim Mulvenna played drums. Jim O'Rourke played piano, "Wurley" played guitar.