Evolution of Early-type Galaxies at Z~1: Differences Between Field and Cluster Populations

The study of the spectroscopic, photometric and morphological properties of early-type galaxies, especially at high redshift and over a range of environmental densities, allows to put constraints on galaxy formation and evolution models. In particular, the presence of old passive stellar populations up to z~1.5 pushes further back the epoch of the last significant star formation episode in massive early-type galaxies. This book presents a study of the star formation history in these high redshift early-type galaxies, in both cluster and field environments, and the novel method used to reconstruct it.