This book presents the edition of all known copies of the important Osirian ritual known as The Lamentations of Isis and Nephthys, along with an extensive commentary. The main copies are a series of papyri from Tebtunis and Thebes, but excerpts are also preserved on some coffins from Thebes and Akhmim. The papyri from the Tebtunis temple library deposit preserve actual manuals used by the priests for the ritual, whereas the other papyri and the coffins preserve copies of excerpts intended for funerary use by private individuals.