This thesis is a study of invisible groups in the religious sphere of Classical Athens. The main focus is the participation by women in religious festivals, with the Anthesteria festival as the main focus of the study. The thesis investigates important aspects of the Athenian society and Greek religion, in order to discuss why women were included in the religious sphere. The Anthesteria festival is chosen for this purpose because it includes aspects of celebration that women normally were not allowed to partake in, as well as aspects that women were required to partake in. The purpose of the thesis is to investigate how and why women were included in the religious celebrations in Athens, whilst they were invisible in other aspects of the Athenian society. The analysis is based on literary sources, mainly selected works by Euripides and Aristophanes, as well as archaeological sources.