Andrea di Michele Cione, called Verrocchio, first trained as a goldsmith and sculptor in marble and bronze, then took up painting sometime in the 1460s. While such masterpieces as the Christ and Saint Thomas at Orsanmichele in Florence or the equestrian statue of Bartolomeo Colleoni in Venice qualify Verrocchio as the leading Florentine sculptor of the day, his oeuvre as a painter is much more problematic. Numerous documents refer to Andrea as a painter, and he is known to have belonged to the painters' confraternity in 1472, but the only extant picture recorded as his, the Virgin and Child Enthroned with Saints (called the Madonna di Piazza, still in situ in Pistoia Cathedral), was, as the recent cleaning demonstrates, almost certainly executed by his pupil and heir, Lorenzo di Credi. A series of small devotional pictures, consisting mostly of half-length Madonnas, is equally problematic. While clearly in his style, these pictures in London, Berlin, and elsewhere, are disputed between the master and the various artists believed to have been his pupils--not only Credi, but also Domenico Ghirlandaio, Perugino, and even Leonardo da Vinci. The only painting of this type which is widely agreed to be autograph is the Virgin with the Seated Child, in the Gemäldegalerie, Berlin. [This is the artist's biography published, or to be published, in the NGA Systematic Catalogue]  Gigetta Dalli Regoli, in Exh. cat. Florence, Maestri e botteghe 1992: 52, cat. 1.5, repro.
The Sculptures of Andrea del Verrocchio. New Haven and London, 1997.
Boskovits, Miklós, and David Alan Brown, et al.
Italian Paintings of the Fifteenth Century. The Systematic Catalogue of the National Gallery of Art. Washington, D.C., 2003: 671.