The String Quintet No. 1 in B flat major, K. 174, was written by Wolfgang Amadeus Mozart in December 1773. Unlike Mozart's other viola quintets, which are scored for two violins, two violas and cello, this early work is scored for two violins, two violas and basso.
The above text from the Wikipedia article "String Quintet No. 1 (Mozart)" text is available under CC BY-SA 3.0.