How galaxies form - and the stars within them - is one of the major open questions of modern cosmology. Early-type galaxies (ETGs) host a large fraction of the stellar mass in today's universe, and typically show no evidence for major ongoing star formation, so they are natural targets for the investigation of how and when galaxy assembly and star formation occurred in the past. The task is a difficult one, which has consumed a large amount of observational and theoretical effort in the past several decades. All that work cannot be fairly summarized in a such short article. This review is thus narrowly focused on what has been learned from stellar ages and abundances based on integrated light studies, and the new questions raised by recent evidence. Apologies go to many hard-working colleagues for any important omissions.