Introduction of the Common Core State Standards and assessments like the synthesis performance task pose new challenges for secondary English teachers. As students of all ability levels engage with complex text and in tasks that target higher level cognitive skills, teachers need strategies to support their understanding. This article describes development and implementation of a differentiated unit for a synthesis performance task in three ninth-grade English classes. The unit's summative assessment required students to evaluate the credibility of survivor accounts of the tragic events atop Mt. Everest in 1996, select the most credible account, and support their argument with evidence from multiple sources. This article includes descriptions of how the unit was differentiated for students of varying skill levels, examples of student work to illustrate how all were able to complete the synthesis task, and reflections for future practice.