A tenet of the Multi-Tiered System of Supports (MTSS) is that even evidence-based interventions will not be effective with all children. We examined preschool children's response to a supplemental literacy intervention ("Story Friends") in two classrooms. Children with weak vocabulary skills were identified and received the intervention. The extremes in children's response to "Story Friends" ranged from highly effective to very ineffective. In one classroom, three children who were not responsive to "Story Friends" received additional intervention components. Two of these children acquired new vocabulary words at rates comparable to highly responsive peers receiving "Story Friends" only, and greater than peers in both classrooms not receiving additional support. The third child was dropped due to refusal to attend sessions. Children's lack of learning the control words demonstrated that their progress on the taught words was not due simply to listening to the words read in the stories.