Monticelli was born in Marseille in humble circumstances. He attended the École Municipale de Dessin in Marseille from 1842 to 1846, and continued his artistic training in Paris, where he studied under Paul Delaroche at the École des Beaux-Arts. In Paris he made copies after the Old Masters in the Louvre, and admired the oil sketches of Eugène Delacroix. In 1855 he met Narcisse Diaz, a member of the Barbizon school, and the two often painted together in the Fontainebleau Forest. Monticelli frequently adopted Diaz's practice of introducing nudes or elegantly costumed figures into his landscapes.