This chapter fills in the background to the composition of the string quartet in 1834. First, we look at Hensel’s early musical education, her intimate creative ties with her brother Felix Mendelssohn, their mutual use of music as a form of intimate communication, and the asymmetrical career path that resulted from her being a woman in contemporaneous society. In parallel to this sibling influence runs the Mendelssohns’ reception of late Beethoven in the 1820s, whose influence on their works of the later 1820s is clear and also has a major bearing on Hensel’s quartet. A final case study showcasing both the interaction with her brother and the music of Beethoven is provided by a brief analysis of the ‘Easter’ Sonata of 1828, which points forward to many features of the string quartet.