AbstractIn this article, we present and analyse phonaesthemic alternations as they appear in Flemish dialects of Dutch, that is when a root-initial consonant or consonant cluster is replaced by a post-alveolar affricate /ʧ/ or /ʤ/ in order to create a phonaesthemically marked variant of a neutral base word. Although no longer productive in Flemish dialects, we show that such phonaesthemic alternations exhibit strong functional similarities to those found in other languages, in particular the evaluative notions of diminutivity and augmentativity. We also show that, formally speaking, Flemish phonaesthemic alternations differ from those attested in other languages in only targeting a single consonant or consonant cluster. We then put forward the hypothesis that Flemish speakers may have copied this mechanism to produce phonaesthemic alternations from Picard speakers, corroborating the notion that phonaesthemic alternations may emerge from language contact.