As the century begins, natural resources are under increasing pressure, threatening public health and development primarily due to accelerating rate of population pressure. Water shortages, soil exhaustion, loss of forests, air and water pollution, and degradation of land and slope failure afflict many areas. As the world's population grows, improving living standards without destroying the environment is a global challenge. The present paper is a gateway to show how the dynamics of population change can bring about a total transformation in the environment, economy and societal aspects of a region. The south districts of Sikkim provide such platform to interpret the dynamism in relation to such aspects. Sikkim has always drawn attention to the researchers from various fields for its unique physical as well as cultural set up. The immigration of people from different parts of the country and outside has brought significant change in all aspects of the State, particularly at the cost of environment. All most all such places throughout the world have negative environmental costing in relation to infrastructural development due to accelerating change of population (growth and density) pattern. Change as is believed is not always positive, hence the present attempt, at the same time, also tries to seek some balanced objectives to do away with the negatives of population growth.