Fluency is an important construct in clinical assessment and in cognitive taxonomies. In the Cattell-Horn-Carroll (CHC) model, Fluency is represented by several narrow factors that form a subset of the long-term memory encoding and retrieval (Glr) broad factor. The CHC broad classification of Fluency was evaluated in five data sets, and the CHC narrow classification was evaluated in an additional two data sets. The results suggest that Fluency tests are more strongly related to processing speed (Gs) and acquired knowledge (Gc) than to Glr, but Fluency may also be represented as a distinct broad factor. In the two additional data sets with a large number of Fluency tests, the CHC Fluency narrow factors failed to replicate with confirmatory factor analysis. An alternative and simpler narrow structure of Fluency was found, supporting the factorial distinction of semantic versus orthographic Fluency. The results have important implications for the factorial structure of memory, the classification of Fluency tests, and the assessment of Fluency.