Objectives: To examine the effect of spirituality and spiritual training on resilience in primary caregiver parents of children with autism spectrum disorders (ASD). Methods: A cross-country pre- and post-test-based experimental design has been used. The sample of this one-year-long study comprised 1687 parents of children with ASD in 15 countries. A six-day customized spiritual lessons package was administered to the study participants. Three scales have been used: Resilience Scale (RS), Sense of Coherence Scale (29-items) (SOC-29), and Parenting and Family Adjustment Scale (PAFAS-30). Results: Results of the paired t-test showed that post-test RS and SOC-29 scores of the participants were higher indicating greater resilience and sense of coherence post treatment. Post-test PAFAS-30 scores were lower indicating lower dysfunction and better adjustment. Logistic regression and structural equation models showed that parents from European countries including the UK, US, Canada, and Australia, Christians, those who did three--four rounds of the spiritual lessons through the study period and those who self-practiced, had higher post-test scores. Further mothers and middle-class parents were likely to have higher post-test resilience scores. Hierarchical regression analysis showed that self-practice was the most significant predictor of participants' post-test scores. Conclusion: The study findings re-inforce the resilience-promoting potential of spirituality/spiritually sensitive interventions for parents of children with ASD, contingent on variations due to domicile country, religion, rounds of spiritual lessons, and self-practice as critical predictors, and sex and economic class as secondary predictors.