This study investigated the value of ACT Composite scores and high school GPA (HSGPA) in predicting first-year college GPA (FYGPA) and degree completion of students with disabilities who took the ACT with accommodations and enrolled at a two-year or four-year public institution in a single state in the southern US. Descriptive analyses found that students who tested with accommodations tended to have lower HSGPAs, lower ACT Composite scores, lower FYGPAs, and lower degree completion rates than their peers who tested without accommodations, which is a finding consistent with prior research. Students who tested with accommodations also tended to have higher correlations between ACT Composite scores and FYGPA than between HSGPA and FYGPA, whereas students who tested without accommodations tended to have higher correlations between HSGPA and FYGPA than between ACT Composite scores and FYGPA. Regression analyses found that models including only ACT Composite scores, accommodation status, and an interaction between ACT Composite scores and accommodation status as predictors were less likely to have statistically significant accommodations or interaction effects (two of seven outcomes). At the same time, all of the models that included HSGPA, accommodation status, and an interaction between HSGPA and accommodation status as predictors had significant interaction effects such that the increase in a given predicted outcome given a one-unit increase in HSGPA was greater for students who tested without accommodations than for students who tested with accommodations. Models including both ACT Composite score and HSGPA together as predictors improved model fit, and statistically significant interactions were found across all outcomes such that the relationship between ACT Composite score and each outcome increased as HSGPA increased, and vice versa. However, for several of the outcomes, significant three-way interactions or significant interactions between HSGPA and accommodations status meant that the increase in a given outcome as ACT Composite score and/or HSGPA increased was greater for students who tested without accommodations than students who tested with accommodations.