The four purposes of this study are: 1) to examine the feasibility of providing children with disabilities to explore the environment with a modified ride-on car; 2) to quantify whether children with disabilities are able to have more social interactions with a ride-on car; 3) to examine the progression of socialization during the intervention and follow-up phases to determine which factors might influence the learning curve; 4) to compare the effectiveness of using the modified toy cars through the hospital-based program and regular therapy program after intervention and follow-up phases to determine the critical factors on increasing independent mobility and socialization, including motivation, treatment executor, treatment environment and play programs. It can provide guidelines for the future intervention.