Spanish-speaking children learn to read words printed in a relatively transparent orthography. Variation in orthographic transparency may shape the architecture of the reading system and also the manifestation of reading difficulties. We tested normally developing children and children diagnosed with reading difficulties. Reading accuracy was high across experimental conditions. However, dyslexic children read more slowly than chronological age (CA)-matched controls, although, importantly, their reading times did not differ from those for ability-matched controls. Reading times were significantly affected by frequency, orthographic neighbourhood size and word length. We also found a number of significant interaction effects. The effect of length was significantly modulated by reading ability, frequency and neighbourhood. Our findings suggest that the reading development of dyslexic children in Spanish is delayed rather than deviant. From an early age, the salient characteristic of reading development is reading speed, and the latter is influenced by specific knowledge about words.