Today's students live within a world filled with complexity, uncertainty, and misinformation; thus, educators need to help all learners, including students with learning disabilities, how to comprehend complex information about the natural world and make credible evidence-based claims. Our study is a first step in making this possible. In this investigation, our goal was for students to make a claim, use evidence and content-specific vocabulary, and then use reasoning to link claims with evidence in an argument. These outcomes were assessed using a pre-post design with a scenario-based assessment administered twice before and once after instruction, which used multimodal STEM text sets to fuse science and literacy learning. Data indicate that (a) both students with disabilities and those without disabilities made significant gains in argumentation and (b) the effects of instruction were similar for both groups of students. Gains for students with disabilities suggest the multimodal STEM text sets provided important scaffolding that enabled this group to learn important content in the general education classroom.