The area used for shrimp aquaculture in Bangladesh has increased about tenfold since 1980. This study examines how shrimp aquaculture has affected the livelihoods of people living beside the Sundarbans mangrove forest in Bangladesh. Using household survey data from 264 households in six villages in Mongla, we found that shrimp income represents 46 % of the total household income for the higher-income households, but just 26 and 8 % for middle- and lower-income households, respectively. Higher-income households were able to derive both larger absolute and relative income from the shrimp sector than the lower-income households, mainly because they had more land initially and used that to acquire ownership or access to most remaining land. This has exacerbated existing inequities so they are greater for shrimp aquaculture than for other livelihoods such as fishing or farming. The expansion of shrimp aquaculture has largely happened by converting agricultural land into shrimp farms. Often this agricultural land was acquired from the poorest people, leaving them even more vulnerable because they have been forced into poorly paid labour or the collection of wild resources from the mangrove forest (often illegal).