The book “Fertility, Mortality and Demographic Change in Assam: A Study of Sonowal Kacharis” is a detail analysis on the pattern of fertility and mortality among the Sonowal Kacharis, the third largest scheduled tribes of Assam, India. It is an endeavour to investigate how different socio-cultural as well as biological factors with special reference to ABO incompatibility influence on fertility and mortality performance of the population considering all other relevant aspects. It contains a comparative discussion on the aspects of fertility and mortality among the studied population and other ethnic groups of Assam as well as Northeast India. This book may be helpful to the students of Anthropology as well as from other disciplines working in the field of demography and population studies. As the book incorporates a detail introduction of the different social and cultural aspects of the population, it may also be helpful for them who are interested to know about the socio-cultural aspects of the Sonowal Kacharis of Assam.