Introduction: Growth faltering (GF) in children is an important public health concern influenced by a complex interaction between psychosocial and demographic factors. Objectives: This study aimed to evaluate the impact of maternal stress, social support, socioeconomic status, and demographic factors on GF severity among children aged 1-3 years in the Western Province, of Sri Lanka. Method: A quantitative, cross-sectional predictive correlational study was conducted with 202 mothers identified as primary caregivers of children experiencing GF. Data were collected at child welfare clinics, conducted by MOH, Colombo, using the Parental Stress Scale (PSS), the Multidimensional Scale of Perceived Social Support (MSPSS), and the Child Health Development Record (CHDR), alongside demographic and socioeconomic information. Data was analyzed using SPSS. Results: Higher maternal stress levels were significantly associated with increased incidence of GF, while social support showed significant negative correlations with GF. Furthermore, family income level and maternal education were negatively correlated, while employment status showed no association with GF. Multinomial logistic regression analyses revealed that higher social support moderated the impact of maternal stress on severe GF cases, and low income amplified the relationship between stress and GF severity . Moreover, maternal stress, social support, and level of education were not significant independent predictors of GF, highlighting the importance of their combined effects. Conclusions: The findings highlight the critical role of combination of maternal stress, social support, and socioeconomic factors in GF severity . Targeted policies reducing stress, strengthening social support, and improving socioeconomic conditions could mitigate growth faltering and enhance child health outcomes.