This article focuses on the reasons for child marriage in a Bangladeshi village. Although the mean age of marriage for women in Bangladesh is currently 20.2, nearly half of all girls are married before the age of 18. In Bangladesh, female sexuality is controlled through early marriage and the custom of purdah, which limits the social interactions between men and women. The methodology of this research was participant observation, supplemented by questionnaires, discussions, interviews and the construction of case studies. The study was conducted in a village in Bangladesh, and looked at why the rural people of Bangladesh marry off their daughters at an early age, whether they think that they will profit from it, and how. Cost-benefit analysis in exchange theory provides the theoretical framework. This study finds that child marriage occurs as a result of the profit-making motive of the people of Bangladesh, despite the huge costs to the individuals involved, the local community and society as a whole.