["Child and Adolescent Mental Health, Volume 31, Issue 2, Page 96-105, May 2026. ", "\n\nBackground\nNeurodevelopmental disorders like autism and ADHD may disrupt family and child functioning. Although well‐established psychosocial treatment programs exist, access to these interventions remains limited for many families. This randomized controlled trial (RCT) primarily evaluates the effectiveness of an online psychosocial program (INPSYD) in improving parental domains (stress, coping, and social support). The secondary aim is to assess its effects on children's domains, including behavior, executive functioning, sleep, and family dynamics.\n\n\nMethods\nThis study employed a two‐arm, mixed‐methods RCT design involving families of children diagnosed with autism or ADHD (mean age 9.28 ± 1.6; 81.1% males), (clinicaltrials.gov, NCT06303791). Participants were randomized to either the intervention group or the active control group (a structured, non‐therapeutic intervention). Outcomes were collected at baseline (before randomization), at 12 weeks post‐randomization, and at 6 months follow‐up after randomization.\n\n\nResults\nA total of 82 participants were randomized in February 2024 (42 to the intervention group and 40 to the active control group). At post‐intervention, participants in the intervention group scored statistically significantly better than those in the control group on measures of parenting stress (p < .01, ηp2 = .29), coping skills (p < .01, ηp2 = .24), and perceived social support (p = .025, ηp2 = .10). Between‐group comparisons also revealed statistically significant differences favoring the intervention group in child social functioning, executive functioning, and family dynamics. No statistically significant between‐group differences were found for sleep problems or learning behavior. These between‐group effects were maintained at the follow‐up assessment.\n\n\nConclusion\nThe results of this study indicate that the INPSYD parenting program is effective for improving parenting stress, coping skills and children's executive functioning and social‐behavioral outcomes in our sample.\n\n"]