Population growth and the environment is now a major discussion issue. Most cases of excessive preference for a larger family size are involved with environmental degradation in developing countries. Moreover, rural or indigenous people living in forest areas have a regular interaction with the environment. They usually depend on environmental resources for subsistence. The main objective of this study is to analyze indigenous people's perception of the relationship between environment and fertility. Out of the seven Khasia villages, the village called Lawachora Punji, with 23 households, was included in the field survey. The research findings reveal that environmental awareness is higher among women and the overall index is relatively low in the indigenous people regarding the environmental and demographic aspects. The overall environmental awareness index (EAI) indicates that people living in Lawachora National Park do not have a strong understanding of the impact of large family size on the environment. Grassroots level participation and gradual change of perception of large family size and dependence on forest resources are important to environmental sustainability in developing countries. Copyright © 2011 John Wiley & Sons, Ltd and ERP Environment.