Identity and attribution
Triptych with the Virgin in the Garden of Paradise
, c. 1445–50. Wallraf-Richartz-Museum, Cologne
There are no signed paintings by Lochner, and his identity was not established until the 19th century.
J. F. Böhmer in an 1823 article identified the Dombild (meaning "Cathedral picture") or Altarpiece of the City's Patron Saints with a work mentioned in an account of a visit to Cologne in 1520 in the diary of
Albrecht Dürer. The notoriously thrifty artist paid 5 silver
 to see an altarpiece by "Maister Steffan" some seventy years after Lochner's death.
 Although Dürer fails to mention specifically which of Maister Steffan's panels he had seen,
 his description matches exactly the centre panel of the Dombild Altarpiece. The altarpiece is referred to in a number of other records. It was repaired and re-
gilded in 1568, and mentioned in
Georg Braun's Civitates Orbis Terrarum in 1572.
German Gothic art underwent a revival in the early 19th century Romantic period, when the work was seen as a climax of the late Gothic period. The German philosopher and critic
Friedrich Schlegel was instrumental in reviving Lochner's reputation. He wrote lengthy tracts comparing the Dombild favourably to the work of
Raphael, and believed it exceeded anything by van Eyck, Dürer or
Goethe was enthusiastic,
 emphasising Lochner's German "spirit and origin"; he described the Dombild as the "axis around which the ancient Netherlandish art resolves into the new".
Lochner's identity remained unknown for centuries, and no other known works were associated with the Dombild altarpiece.
 In 1816
Ferdinand Franz Wallraf identified him as Philipp Kalf, based on a reading of a name inscribed on the cloth of a figure on the right of the centre panel. He misinterpreted markings on the stone floor pictured in
Annunciation to read 1410, which he took as the year of completion.
Johann Dominicus Fiorillo discovered a 15th-century record that read "in 1380 there was an excellent painter in Cologne called Wilhelm, who had no equal in his art and who depicted human beings as if they were alive".
 In 1850
Johann Jakob Merlo identified "Maister Steffan" with the historical Stefan Lochner.
Gustav Waagen became one of the first art historians to try to place Lochner's works in chronological order. His reasoning was based the assumption that Lochner developed from the early idealised forms usually associated with early 15th century Cologne, and later absorbed the techniques and realism of the Netherlandish painters. In this way he placed the lighter "gaiety" of Lochner's Madonna paintings as from the beginning of his career, with the more stern and pessimistic crucifixions and doom panels at the end. Today, art historians believe the reverse to be true; the dramatic and innovative polyptychs came first, and the single Madonnas and panels of saints are from his mid career.
Based on their similarity to the Altar of the City Patrons, art historians have attributed other paintings to Lochner, although a number have questioned whether the diary entry was authentically made by Dürer. Documentary evidence linking the paintings and miniatures with the historical Lochner has also been challenged, most notably by the art historian Michael Wolfson in 1996.
 In either case, the extent of Lochner's direct hand, as opposed to those of workshop members or followers, is debated.
 Some panels formerly attributed to him are now thought to date from after 1451, the year of his death.