Alberti bass

thumb|300px|Mozart's Piano Sonata, K 545 (1788) opening.

300px|thumb|Equivalent patterns in and and

thumb|300px|Alberti bass patterns on V⁷

thumb|300px|Alberti bass in the opening of [[Thomas Attwood (composer)|Thomas Attwood's (1765–1838) Sonatina in G Major ]]

thumb|300px|Alberti bass in the opening of [[Muzio Clementi's Sonatina in G, Op. 36, No. 2 (1797) ]]

Alberti bass is a particular kind of accompaniment figure in music, often used in the Classical era, and sometimes the Romantic era. It was named after Domenico Alberti (1710–1740/46), who used it extensively, although he was not the first to use it.

Alberti bass is a kind of broken chord or arpeggiated accompaniment, where the notes of the chord are presented in the order lowest, highest, middle, highest. This pattern is then repeated several times throughout the music.

Alberti bass is usually found in the left hand of pieces for keyboard instruments, especially for Mozart's piano pieces. However, it is also found in pieces for other instruments. It has been described as "a true tolerable monotony," and as "perhaps the most overworked fixture of eighteenth-century music."

Well-known examples of Alberti bass include the beginning of Mozart's Piano Sonata, K 545, and the third movement of Beethoven's Moonlight Sonata.