The galaxy population evolution of Sunyaev
b'This thesis presents a study of the galaxy populations in massive galaxy clusters that have been selected via the Sunyaev - Zeldovich Effect from the South Pole Telescope. The clusters have multiband optical imaging data from the Dark Energy Survey (DES). Each cluster has a robust mass estimate and with the deep DES data they cover a redshift range between 0 and 1.1. This makes it an ideal cluster sample to study evolutionary trends of the galaxy populations with mass and redshift.'