"Puttin' on the Ritz" is a pop song written and published in 1929 by Irving Berlin and introduced by Harry Richman in the musical film Puttin' on the Ritz (1930). The title derives from the slang expression "putting on the Ritz," meaning to dress very fashionably. The expression was inspired by the swanky Ritz Hotel.

The song is in AABA form, with a verse.
According to John Mueller, the central device in the A section is the "use of delayed rhythmic resolution: a staggering, off-balance passage, emphasized by the unorthodox stresses in the lyric, suddenly resolves satisfyingly on a held note, followed by the forceful assertion of the title phrase." The marchlike B section, which is only barely syncopated, acts as a contrast to the previous rhythmic complexities.
According to Alec Wilder, in his study of American popular song, the rhythmic pattern in "Puttin' on the Ritz" is "the most complex and provocative I have ever come upon."

The original version of Berlin's song included references to the then-popular fad of flashily-dressed but poor black Harlemites parading up and down Lenox Avenue, "Spending ev'ry dime / For a wonderful time". The song was featured with the original lyrics in Idiot's Delight (film) (1939) where it was performed by Clark Gable and chorus, and this routine was selected for inclusion in That's Entertainment (1974). For the film Blue Skies (1946), where it was performed by Fred Astaire, Berlin revised the lyrics to apply to affluent whites strutting "up and down Park Avenue."

Hit phonograph records of the tune in its original popularity of 1929-1930 were recorded by Harry Richman and Fred Astaire, with whom the song is particularly associated.
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