Weinen, Klagen, Sorgen, Zagen (Weeping, lamenting, worrying, fearing), BWV 12, is a church cantata by Johann Sebastian Bach. He composed it in Weimar for Jubilate, the third Sunday after Easter, and led the first performance on 22 April 1714 in the Schlosskirche, the court chapel of the Schloss in Weimar.

Bach was appointed Konzertmeister in Weimar in the spring of 1714, a position that called for the performance of a church cantata each month. He composed Weinen, Klagen, Sorgen, Zagen as the second cantata in the series, on a text probably written by court poet Salomon Franck. The work is structured in seven movements, an instrumental Sinfonia, a choral passacaglia, a recitative on a Bible quotation, three arias and, as the closing chorale, the last stanza from Samuel Rodigast's hymn "Was Gott tut, das ist wohlgetan" (1674). The cantata is scored for three vocal soloists, a four-part choir, trumpet, oboe, bassoon, two violins, two violas, and basso continuo.

Bach performed the cantata again in his first year as Thomaskantor – director of church music – in Leipzig, on 30 April 1724. He reworked the first section of the first chorus to form the Crucifixus movement of the Credo in his Mass in B minor. Franz Liszt based extended keyboard compositions on the same material.