This study investigates the etymological origin of the family of the Greek adjective καλός ‘beautiful’ from the parent language Proto-Indo-European (PIE). After examining its use in archaic hexameter poetry and reviewing previous proposals, the author situates the problem in the broader context of the morphological behavior of Greek and PIE roots of adjectival meaning, and pursues evidence for derivation from the root *ḱel- ‘cover’ in light of the larger categories of nominal derivation in PIE. By means of etymological analysis of semantically comparable lexemes, the dissertation finally explores the conceptual relationships involved in the emergence of the lexical meanings of the forms ancestral to καλός and its relatives.