Broad scientific concepts are vital to individual wellbeing as a function of daily living skills. Science connects how individuals interact with the environment and how they interpret those interactions (Browder et al, 2007). According to the National Assessment of Education Progress, students with disabilities score significantly lower than students without IEPs on standardized science achievement assessments (National Center of Education Statistics, 2015). In addition, students with intellectual and developmental disabilities (IDD) are likely to be left out of opportunities to learn science content regardless of educational setting. The current study examines and analyzes published single-case research (SCR) on science and science-related achievement for students with IDD through Tau-U effect size analysis and rigor evaluation. Implications for research and teaching are discussed.