<p>While there has been a considerable conceptual discussion of trapped populations in the environmental migration literature, the empirical evidence on their existence is scarce. I examine why many people remain in environmentally vulnerable areas by analyzing newly collected survey panel data of 1515 household heads living along the Jamuna River in Bangladesh, an area affected by riverbank erosion and flooding. To examine whether immobility is voluntary or involuntary, I assess the migration aspirations and capability to move of those who did not migrate after environmental shocks occurred in their village. The majority (82%) of non-migrants can be classified as voluntary non-migrants, while 13% can be considered “trapped” and the remaining 5% as acquiescent non-migrants. Being affected by erosion significantly increases the likelihood that immobility is involuntary by 7.9 percentage points, while also lowering the socio-economic status of the affected population. Taken together, these results suggest that environmental change may indeed lead to the “trapping” of parts of the population in exposed areas by eroding their capability to move while simultaneously increasing their migration aspirations. The findings have important policy implications, as they raise a word of caution against prematurely labeling all populations staying in environmentally exposed areas as “trapped” without considering their migration aspirations—a majority may in fact be voluntary non-migrants.</p>