Madonna and Child with Mary Magdalene and St Dorothea

Ambrogio Lorenzetti (Italian pronunciation: [amˈbrɔːdʒo lorenˈtsetti]; c. 1290 – after 9 August 1348) was an Italian painter of the Sienese school. He was active from approximately 1317 to 1348. He painted The Allegory of Good and Bad Government in the Sala dei Nove (Salon of Nine or Council Room) in the Palazzo Pubblico at Siena. His elder brother was the painter Pietro Lorenzetti.

Lorenzetti was highly influenced by both Italo-Byzantine art and classical art forms, and used these to create a unique and individualistic style of painting. His work was exceptionally original. Individuality at this time was unusual due to the influence of patronage on art. Because paintings were often commissioned, individualism in art was infrequently seen. It is known that Lorenzetti engaged in artistic pursuits that often were thought to have their origins later during the Renaissance, such as experimenting with perspective and physiognomy, and studying classical antiquity. His body of work clearly shows the innovativeness that subsequent artists chose to emulate.

His work, although more naturalistic, shows the influence of Simone Martini.