This study investigated the processes involved in the aging of semantic categorical flexibility. A previous study revealed the effects of aging on the flexible use of taxonomic relations. We aimed to explain our previous results regarding the performance of older adults; we carried out investigations into the respective roles of executive and conceptual factors in semantic categorical flexibility. Fifty older adults carried out a semantic categorical flexibility task alongside conceptual and executive measures. The results replicate our previous findings and indicate that the predictors of the maintenance of the use of taxonomic relations are conceptual and the predictors of the switching from thematic to taxonomic relations are executive.