We report a study of the factors that affect reading in Spanish, a language with a transparent orthography. Our focus was on the influence of lexical semantic knowledge in phonological coding. This effect would be predicted to be minimal in Spanish, according to some accounts of semantic effects in reading. We asked 25 healthy adults to name 2,764 mono-and multisyllabic words. As is typical for psycholinguistics, variables capturing critical word attributes were highly intercorrelated. Therefore, we used principal components analysis (PCA) to derive orthogonalized predictors from raw variables. The PCA distinguished components relating to (1) word frequency, age of acquisition (AoA), and familiarity; (2) word AoA, imageability, and familiarity; (3) word length and orthographic neighborhood size; and (4) bigram type and token frequency. Linear mixed-effects analyses indicated significant effects on reading due to each PCA component. Our observations confirm that oral reading in Spanish proceeds through spelling-sound mappings involving lexical and sublexical units. Importantly, our observations distinguish between the effect of lexical frequency (the impact of the component relating to frequency, AoA, and familiarity) and the effect of semantic knowledge (the impact of the component relating to AoA, imageability, and familiarity). Semantic knowledge influences word naming even when all the words being read have regular spellingsound mappings.Keywords Spanish . Reading . Naming . Age of acquisition . Orthographic transparency . Curvilinear A general account of the cognitive reading system must describe and explain the effects of word attributes on reading in different orthographies. Orthographies may differ in a range of ways, but there has been a long-standing interest in how reading varies in relation to differences in orthographic transparency (e.g., Frost, Katz, & Bentin, 1987). The Spanish orthography is transparent because orthography-phonology mappings are completely rule governed across the language (Cuetos & Barbón, 2006). In comparison, the English orthography is quasi-regular, having both rule-governed and exceptional orthography-phonology mappings (Plaut, McClelland, Seidenberg, & Patterson, 1996). Current evidence suggests that reading is affected by a mix of factors that appears to be similar in kind, whether more opaque or more transparent orthographies are examined. Our aim was to bring evidence to bear on whether reading effects would be similar, also, in the specific components. We were especially concerned with the impact on reading of the key lexical factors-frequency, age of acquisition (AoA), and imageability (seen to affect reading in English; e.g., Balota, Cortese, Sergent-Marshall, Spieler, & Yap, 2004;Cortese & Khanna, 2007)-and with the question of whether previous observations of the AoA effect on reading in Spanish (Cuetos & Barbón, 2006) can be taken to reveal the influence of semantics on word naming in a transparent orthography. (Balota et al., 2004;Cortese & Khanna, 2007)...