Recent Indian studies indicate stagnation in decline of child mortality, though various health care interventions were introduced during the last 2 decades. This study examined the rates of infant and child mortality and associated demographic and socioeconomic factors in 2 socioeconomically vulnerable populations, comprising 195 Munda and 334 Poundrakshatriya women having similar access to health care facilities in a periurban region of Kolkata city. Higher infant mortality rate (IMR) was noted in the older and younger Munda women, in contrast to lower IMR in younger Pod women. Child mortality rate was lower in younger women in both the ethnic groups. Stagnation in IMR in younger Munda women indicates poor delivery practices whereas lower rate among the Pod reflects better adoption of safe delivery practices. Differential association of factors with infant and child deaths in the 2 populations indicate that a better understanding of determinants in culturally heterogeneous populations at the community or household level is needed to develop more effective strategies for child survival and development.