Students with and without learning disabilities in high school chemistry classes, either co-taught or self-contained, received instruction on calculating molar conversions using universal design for learning (UDL) or business-as-usual techniques. For Study 1, posttest scores of students with and without learning disabilities (LD) in co-taught classes who received the UDL treatment are compared with peers' scores in the comparison group. For Study 2, posttest scores from students with LD who received UDL treatment in a self-contained special education class are reported. Students in the UDL treatment scored significantly higher on posttests than comparison group peers in Study 1. Mean scores for students with LD in Study 2 were similar to UDL students in Study 1. Social validity feedback on the UDL instruction was positive. Implications for UDL chemistry instruction and future research are described.