The central aim of this study was to clarify whether sign language (SL) nativeness is a significant factor in determining prelingually deaf individuals' reading skills and whether its contribution is modified by the reader's orthographic background. A second aim was to elucidate similarities and differences between native and nonnative signers in processing written information at different processing levels in order to understand how SL nativeness sustains the reading process, if at all. Participants were 176 students with prelingual deafness recruited from two education levels (6th-7th graders and 9th-10th graders) and three orthographic backgrounds (Hebrew, German, and Turkish). Sixty-six students were native and the remainder nonnative signers. They were tested with a battery of eight experimental paradigms, each assessing their information processing skills in a specific reading-related or reading-unrelated domain. Findings corroborate SL nativeness enhancing the reading process in some regard. However, its contribution was not found to scaffold the structural processing of a written text to turn reading into a tool for learning. Rather, gains were restricted to facilitating processing written words from a perceptual to a conceptual level. Evidence suggests that compared with other determining factors, the contribution of SL nativeness to proficient reading may be rather marginal.