Background: A child brings happiness, love and joy in the family and society and if a child born with Intellectual Developmental Disability (IDD), then parenting of IDD children requires a huge amount of liability, accountability, commitment and dedication. Children with intellectual disability are having debilitate physical and mental health conditions, lower longevity1. As parents are the primary caregivers, but lives of parents of children with IDD are much more complicated and stressful as compared to the lives of non-disabled childrens parents. Methodology: Quasi-experimental Time Series Research Design was used to assess the effectiveness of Parenting Skill Program on childs adaptive behavior among parents of children with Intellectual developmental disability in selected Special Schools of Delhi NCR.The tools used for data collection included a socio-demographic proforma and the Vineland Social Maturity Scale (VSMS). Structured interviews and pre-assessment tools, such as socio-demographic proforma and the Vineland Social Maturity Scale (VSMS), were administered to both experimental and control groups in the first month. Subsequently, the parenting skills program, consisting of 12 sessions, was implemented over a three-month period, with one session per week for parents in the experimental group. At the 6th, 9th, and 12th months, structured interviews using post-assessment tools were conducted with parents from both groups. Results: The findings of the study revealed thatthere was an improvement in the mean posttest score of childs adaptive behavior over the time. Specifically, at 6th month, it increased to (53.425±8.95), followed by (52.850±9.77) at 9th month and (55.288±8.87) at 12th month when compared to baseline score (46.362±8.09).This increase was found to be statistically significant within the group (F= 163.040, p 0.001).However, the control group, showed no significant change in the mean score of childs adaptive behavior and it remained same in 6th month, 9th month and 12th month as baseline, and no significant difference was observed within the group (F= 6.00, p 0.112). Hence, it could be interpreted that parenting skill program was effective in improving the childs adaptive behavior score of children with IDD in experimental group than in control group. Conclusion:It was concluded thatparenting skill program was effective in improving the childs adaptive behavior of children with IDD.