A growing body of evidence suggests that deaf signers are highly efficient readers of English – they read faster than monolingual English-speakers who have equivalent comprehension abilities. In addition, deaf signers have larger reading spans, the area around fixation from which useful information is extracted. The current study investigated the relationship between reading rate, reading comprehension ability, and the sizes of two types of reading spans: the word identification span (i.e., the area from which linguistic information is extracted) and the perceptual span (i.e., the area from which the visuo-spatial layout of text is extracted). These relationships were assessed in a large group of deaf signers (N = 50) and hearing non-signers (N = 109). Both groups showed a positive relationship between the size of the word identification span and reading rate, but only the deaf group showed a positive relationship between reading comprehension ability and reading rate, and between reading comprehension ability and word identification span size. These findings suggest that one source of deaf signers' reading efficiency is their use of the word identification span to support both reading speed and their ability to understand English text.