Parent involvement is a predictor of postsecondary education and employment outcomes, but rigorous measures of parent involvement for youth with disabilities are lacking. Hirano, Garbacz, Shanley, and Rowe adapted scales based on Hoover-Dempsey and Sandler model of parent involvement for use with parents of youth with disabilities aged 14 to 23. This study assessed the psychometric properties of the Motivators of Parent Involvement (MPI) scales. A confirmatory factor analysis tested an 11-factor model, three parent involvement factors, and eight motivators of involvement factors for parents of transition-age youth (ages 14-25) with disabilities. Using a sample of 288 parents and caregivers, the model was determined to have acceptable fit. The MPI can be used to assess motivators of parent involvement and guide interventions.