Maternal parental self-efficacy is a crucial factor for facilitating the smooth transition into motherhood, particularly for primiparas. The aims of this study were to examine the predictors of maternal parental self-efficacy and its relationship with social support, postnatal depression (PND), and socio-demographic variables of primiparas during the early postnatal period. A descriptive correlational study design was adopted. The instruments, Perceived Maternal Parental Self-Efficacy, Perinatal Infant Care Social Support, and Edinburgh Postnatal Depression Scale, were used to collect data from a purposive sample of 122 primiparas on the day of discharge (1-3 days post delivery) in a tertiary public hospital in Singapore. There were significant correlations among maternal parental self-efficacy, social support, and postnatal depression. The main predictors of maternal parental self-efficacy were social support, ethnicity, maternal age, and family income. The maternal parental self-efficacy, social support, and PND should be routinely assessed to provide necessary support to needy mothers.