The past forty years in particular have witnessed a vast amount of investigations into decoding the aims and procedures of ancient Greek mystery cults. More recently, a number of rigorous and insightful studies have dealt with issues of definitions and reconstructions of the mystic proceedings.1 However, mystery cults, given their strong cosmological focus and predominantly nocturnal elements,2 call for investigations that take into account the context of the season, time, and skyscape in which they were performed. Because the ancient night sky is a piece of evidence more directly accessible than many other aspects of symbolic language and associations, such a study has the potential to illuminate and enrich our understanding of cult rites of which very little is otherwise known. Thus, this chapter aims to complement earlier studies by providing the crucial temporal context of three mystery cults: Eleusis, Lykosoura, and Samothrace. To achieve this, it is essential to know the month, or at least the season, when initiation was performed. As a result, we are limited in our analysis. The case of the mysteries of Despoina in Lykosoura, for instance, the timing of which is not known, demonstrates these limitations when compared to the better-documented Eleusinian Mysteries.