Is there an achievement gap for online reading ability based on income inequality that is separate from the achievement gap in traditional, offline reading? This possibility was examined between students in two pseudonymous school districts: West Town (economically advantaged) and East Town (economically challenged; N = 256). Performance-based assessments were used within a simulation of the Internet developed as part of a larger project. Seventh graders completed two online research and comprehension assessments, which evaluated four skill areas (locate, evaluate, synthesize, and communicate) and two knowledge domains in science. Students also completed an assessment of prior domain knowledge and a short Internet use questionnaire. Standardized state reading and writing test scores served as measures of offline literacy skills. Results indicated that there was a significant achievement gap favoring West Town students in offline reading scores, offline writing scores, and online research and comprehension scores. A significant gap persisted for online research and comprehension after we conditioned on pretest differences in offline reading, offline writing, and prior knowledge scores. The results of the questionnaire indicated that West Town students had greater access to the Internet at home and were required to use the Internet more in school. These results suggest that a separate and independent achievement gap existed for online reading, based on income inequality. Current estimates of this gap, which rely solely on measures of offline reading, may underrepresent the true nature of the U.S. reading achievement gap in an online age. Policy implications are explored.