Proto-Indo-European reconstruction is informed by the study of more than 80 distinct languages, living and extinct, each with their own individual sound patterns and phonological evolution. In this chapter, directly inherited Proto-Indo-European sound patterns as well as notable and common sound changes within the Indo-European family are compared with sound patterns and sound changes in Proto-Basque as reconstructed in Part I. This typological comparison is not meant to prove genetic relatedness, but does lend some plausibility to the patterns and developments hypothesized for Euskarian on the basis of internal reconstruction and for the suggestion of an ancient relationship between the two language families, which pre-dates the breakup of Indo-European somewhere between Eastern Europe and the Aral Sea around 5000 bc. Special attention in this chapter is given to sound patterns shared by Proto-Basque and Common Anatolian, as well as Euskarian sound changes with Indo-European parallels, including Grassmann’s Law, and the split of *s as a result of *s-laminalization in clusters.