Human development is determined by both genetic and environmental factors, especially during early childhood. Recently, research has indicated that the circumstances surrounding poverty can significantly influence children’s development. In this study, we aimed to measure the developmental level of children living in low-income, rural areas in northern Colombia. A total of 629 children (aged 0–5 years) were assessed using the Battelle Developmental Inventory. Results indicated that 17 % of the participants had a general developmental delay for their age group. This was especially true for scores on cognitive development (35.5 %) and communication (21.5 %). Moreover, the number of children with developmental delay increased at 6 months of age and continued to increase after 1 year in the communication and cognitive domains. The findings of this study suggest that impoverished social contexts—such as the one studied herein—offer opportunities that favor the development of the social domain, but restrict the development of the cognitive domain. Therefore, to promote cognitive development, individuals within children’s environment need to actively and intentionally stimulate them. Thus, there is a need for interventions that will improve environmental conditions; especially those that will help parents improve their caregiving practices and train educational staff to recognize and respond to the stimulation needs of children, especially those developmental domains that are affected by the environment.