The String Quartet in B flat major (K. 172) is one of a series of six quartets Mozart composed in the late summer and early fall of 1773, probably in Vienna, a few months after returning from a tour of Italy. While the set of quartets composed near the end of his travels (K. 155-160) clearly exhibited the young composer's absorption of the musical styles and forms encountered during his Italian tour, the set of "Viennese" quartets in which K. 172 appears (K. 168-173) betrays the recent influence of Haydn's early quartets Opp. 17 (1771) and 20 (1772) both in terms of character as well as form. The K. 172 quartet exemplifies the waning phase of Mozart's transition from a calculatedly impressionable early phase to a mature and distinctive voice.
