This study examined the relative contribution of reading comprehension strategies and interactive vocabulary in Improving Comprehension Online (ICON), a universally designed web-based scaffolded text environment designed to improve fifth-grade monolingual English and bilingual students' reading achievement. Seventy-five monolingual English and 31 bilingual students from six classrooms were assigned to one of three ICON conditions: reading comprehension strategies, vocabulary, or a combined version of comprehension strategies and vocabulary. Students read eight multimedia folktales and informational texts within their respective ICON condition and completed embedded activities, researcher measures of comprehension and vocabulary, and pre- and postintervention standardized reading achievement tests. ANCOVA results indicated that after controlling for initial reading achievement, there was a main effect for condition on the researcher measure of vocabulary, with the combination group and vocabulary groups both significantly outperforming the strategy group. There was also an interaction effect, with differences between monolingual and bilingual Spanish-speaking students greatest in the strategy group. There was no effect of condition on comprehension, nor was there an effect of language status on narrative comprehension. However, there was a main effect of language status on expository text comprehension and standardized vocabulary achievement, with monolingual students performing more strongly than bilingual Spanish-speaking students. The results add to a growing body of research on the design and use of scaffolded digital text for diverse learners. (Contains 6 figures and 6 tables.)