Scoring: Coro SSATB, 2 Fl, 2 Ob, 2 Cor, 2 Tr, 3 Trb, Timp, 2 Vl, Va, Vc/Cb

In 1827, shortly after a stay with Thibaut in Heidelberg, "Tu es Petrus" was composed, an echo of his contact with the style of Palestrina. Mendelssohn himself considered the work, which uses and artful and strictly contrapuntal development of the motif, the "most successful piece" of that year.