Objective: Few randomized controlled trials (RCTs) have explored the implementation and impact of early childhood parenting education programs in very fragile contexts and humanitarian settings. We tested the effects of a group-based intervention, the MotherÀChild Education Program (MOCEP), on parenting stress and practices among two refugee communities and one other marginalized community in Beirut, Lebanon. Method: A pilot wait-list RCT was conducted to assess the program's impact on maternal, child (average age: 4 years), and dyadic outcomes. A total of 106 motherÀchild dyads were randomly assigned to either the intervention group (n ¼ 53) or the wait-list control group (n ¼ 53). Analysis was conducted by modified intention-to-treat and supplemental analyses through multiple imputation of missing post-intervention data. Results: Forty families (38%) withdrew early from the study. After completing the program, mothers in the intervention group showed a reduction in their harsh parenting practices, as indexed by the Disciplinary Style Questionnaire (Cohen's d ¼ À0.76, 95% CI ¼ À1.24, À0.27) and in their level of parenting stress, as indexed by the Parenting Stress IndexÀShort Form (PSI-SF; Cohen's d ¼ À0.90, 95% CI ¼ À1.39, À0.40). Exploratory but underpowered analyses of dyadic interactions revealed reductions in the PSI were associated with a reduction in harsh parenting after the intervention. However, we did not detect any positive impact on behavioral or emotional outcomes among the children. Conclusion: Our analyses suggest that MOCEP had a positive impact on disciplinary practices and parenting stress in a context of high fragility, but that broader effects on maternal and child outcomes may be dependent on program attendance and the availability of other services. We discuss implications of this pilot study for practice and research of a largely unexplored area of program evaluation. Clinical trial registration information: Mother and Child Education Program in Palestinian Refugee Camps; https://clinicaltrials.gov; NCT02402556.