Purpose:To examine the effects of task-oriented activities based on neurodevelopmental therapy (TOA-NDT) principles on trunk control, balance, and gross motor function in children with spastic diplegic cerebral palsy (SDCP).Materials and Methods:Forty-four children with SDCP, aged 7–15 years, were recruited to participate in the randomized clinical trial. After random allocation, twenty-two (n = 22) children with SDCP participated in TOA-NDT principles and twenty-two (n = 22) in conventional physiotherapy (CPT) program. Each group underwent the treatment for a duration of 60min per day, 6 days a week for 6 weeks. Gross motor function measure-88 (GMFM-88), postural assessment scale (PAS), pediatric balance scale (PBS), and trunk impairment scale (TIS) were the outcome measures used to document the pre- and post-intervention effect.Results:The mean difference of GMFM-88, PAS, PBS, and TIS was 8.53 (5.84–11.23), 0.90 (5.84–11.23), 4.86 (2.93–6.79), and 1.45 (0.30–2.60), respectively. TOA-NDT group showed improvement in all the outcomes.Conclusion:TOA-NDT principles are more beneficial in improving the trunk control, balance, and gross motor function parameters than CPT.