He was an assistant to the painter Giotto and the father of the painters Giovanni Gaddi, Agnolo Gaddi and Niccolò Gaddi; his fourth son, Zanobi, does not appear to have been an artist.
The Stigmatization of Saint Francis (http://www.artmuseums.harvard.edu/collections/servlet/webpublisher.WebCommunication?ia=codetail&ic=basic&oid=854&sq=1&tr=1&tech=) (c.1325-1330), tempera on wood panel
Madonna and Child Enthroned (http://www.arca.net/uffizi/img/Ap027.jpg) (1335), tempera on wood
Giorgio Vasari included a biography of Taddeo Gaddi in his Lives.
The father died in 1366, Giovanni in 1383, Agnolo in 1396, and all three are buried in Santa Croce in Florence.
Taddeo was the godson of Giotto, lived with him twenty-four years, and became the most eminent of his numerous scholars.
Giovanni Gaddi, the brother and pupil of Agnolo, was a man of much less importance, and hardly any works now remain which can be attributed to him with certainty, as in the rebuilding of San Spirito at Florence most of his work was destroyed.