The present study is intended to understand the socio-economic vulnerability under a changing climate for coastal communities that are dependent on mangroves ecosystems in two important South Asian deltas: the Indus and Ganges-Brahmaputra. We use the Composite Vulnerability Index (CVI) approach to draw a general picture of vulnerable communities. We try to answer some key questions to understand how climate change is impacting mangrove ecosystems and dependent communities. Our assessment shows that these coastal communities are highly sensitive and exposed to climate change-driven threats. Further, poor access to basic facilities, inadequate income diversification, and low education levels are negatively affecting adaptive capacity of local populations. However, the communities’ nature of dwelling, their strong family networks, and their ability to migrate on a timely basis when the need arises contribute to their adaptive capacity.