The goal of this paper is to lay out the outcomes in the various Greek dialects of the Proto-Indo-European segment *y in all environments. I begin with Mycenaean which already shows some of the developments which are fully complete by the Classical Greek period. After this, the analysis of outcomes in Classical Greek is broken down by specific environment: word-initial position, intervocalically, and in consonant clusters which are divided by manner of articulation. Additionally, dialectal variations of the outcome of each cluster are noted. The last section contains a few observations on the importance of some of these outcomes and offers a more specific explanation of how they developed.