In developing countries including rural India, undernutrition among preschool children is one of the main barriers of the national development. However, there exists scanty information on the prevalence of underweight and stunting and their socio-demographic predictors among preschool children in India and West Bengal. The aim of the present study was to investigate the prevalence of underweight and stunting and the impact of two socio-demographic indicators, namely number of living rooms (NLR) and number of sibs (NS), on them among 1-5 year old Bengalee rural preschool children of Integrated Child Development Services (ICDS) Centres. This cross sectional study was undertaken at 30 randomly selected ICDS centre of Chapra Block, Nadia District, West Bengal, India. A total of 673 children, aged 1-5 years were studied. The overall (age and sex combined) rates of underweight and stunting were 54.40% and 39.20%, respectively. NLR was significantly associated with the prevalence of underweight (chi2 = 4.34, df = 1, p < 0.05) and stunting (chi2 = 8.98, df = 1, p < 0.01) among girls. Similarly, NS had a significant association with prevalence of underweight (chi2 = 10.29, df = 1, p < 0.001) and stunting (chi2 = 5.42, df = 1, p < 0.05) among girls. Girls with < 2 NLR had significant higher risk of being underweight (OR = 1.64, C.I = 1.30-2.62) or stunted (OR=2.23, C.I = 1.31-3.80) than those with > or = 2 NLR. Moreover, girls with > or = 3 NS had significant higher rate of underweight (OR = 2.03, CI = 1.32-3.146) or stunting (OR = 1.69, C.I = 1.09-2.63) than those with < 3 sibs. Logistic regression analyses also revealed that both NLR as well as NS were strong predictors of underweight (NLR: Wald = 4.30, p < 0.05; NS: Wald = 8.74, p < 0.001) and stunting (NLR: Wald = 10.17, p < 0.001; NS: Wald = 5.38, p < 0.05) among girls. Gender discrimination could be a likely cause for this sex difference in the impact of NRL and NS. Moreover, logistic regression were also undertaken with underweight and stunting status (yes/ no) as dependent variables and NLR and NS (combined) as independent variables to identify their effects, when considered together, on undernutrition. Results showed that NS had significant impact on underweight (Wald = 8.28, p < 0.001) rather than NLR among girls. Results also demonstrated that NLR had significant impact on stunting (Wald = 6.874, p < 0.01) rather than NS.