One would not expect that Philo’s About Those Whose Names Are Changed and Why They Have Their Names (De mutatione nominum) and Plutarch’s On Isis and Osiris would have much in common. On a micro scale, however, Philo treats why the protagonists of Genesis received new names or had alternate names (which involves just about everyone). On the macro scale, however, the names in Genesis lead to an inspiring allegorical interpretation heavily influenced by Greek philosophy, especially Middle Platonism, leading the reader to high ethical behavior and finishing with a crescendo on the one God, the God of Israel. Plutarch in turn uses etymologies on a micro scale to explain the names involved in the Isis cult, which also lead to an inspiring allegorical interpretation of the nature of God. Unlike Philo, he begin with a long programmatic statement about the goal, and toward the end develops the major allegory, an understanding of God and the destiny of the soul, as developed in Middle Platonism. There have been many recent etymological studies of Philo, e.g. Winston (1991), Niehoff (1995), Long (1997), Runia (2004), Shaw (2015), and Attridge (forthcoming). In contrast, we find little on the Plutarchan side, except for treatment in the commentaries on De Iside, e.g., Gwyn-Griffiths (1970), Hani (1976), Froidefond (1988) and studies mainly interested in the implications of the etymologies, e.g., Richter (2001 and 2011) and Brenk (1999 [2008]). Plutarch was at a disadvantage, since he was working with an unfamiliar religion and language and could not consult living experts. His task was also complicated, since to justify Greek etymologies he makes the preposterous claim that many Egyptian words were really Greek, adopted by Egyptians in the ancient past from Greeks in Egypt. Unlike Philo, Plutarch could dedicate only about 10 percent of his treatise to the etymologies and about 12 percent to the allegorical interpretations. Contrary to the impression of his dictum “Isis is a Greek word.,” his Greek etymologies of Egyptian words are basically (and very unconvincingly) relegated to the names of Isis, Osiris, and Sarapis (e.g. 362C, 364D, 375C-E). He offers at least 16 Egyptian etymologies or interpretations of names, some of them taken from an excellent Egyptian source, Manethon, or from Greek authorities. To some Egyptian etymologies he also adds Greek ones. Like Philo, he is interested in alternate names, and, as in Philo, the etymologies can lead to an allegory or even to an allegorical narrative. Of particular interest are such etymological explications as Philo on Isaac (157, 166-167) and Plutarch on Sarapis (362D), and slightly extended allegories (Philo, 97-105; Plutarch, 368E-F), or the use of texts (e.g. Plutarch, citing Plato, 374C-E). Innumerable etymologies in both authors involve wisdom and knowledge or coming to know the divine. The paper will explore, though individual cases, their common cultural and philosophical heritage, their common goals, the differences between them, and scholarly reactions to their work.