Schubert's Allegretto in C major, D. 900, is a charming and graceful waltz. Its delicate melody and gentle accompaniment create a feeling of sweet melancholy.
Cultivating a sensitive touch and understanding the expressive potential of rubato are key.
Alegretto (D.900) is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 3.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Alegretto (D.900) lasts about 2 minutes.
Alegretto (D.900) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.