This article is concerned with how far-reaching economic and ecological changes are affecting the livelihoods of coastal households in Vietnam. In particular, we are interested in the livelihood effects of two aspects of this changing environment: (1) the transformation of the fisheries sector, including declining stocks and species loss and the rapid expansion of aquaculture, and (2) the broader structural change in the Vietnamese economy, from household-based primary-sector activities to wage and salary employment and self-employment outside the household. Our analysis, based on a survey of 599 households in 12 coastal communes in two provinces, shows considerable changes in livelihood patterns over the decade covered by the survey. Over one-third of the responding households reported a different primary earnings source in 2012 than in 2002. Fewer relied on aquaculture as their main livelihood activity in the later year. While aquaculture, encouraged by official policy, has assumed an increasingly dominant position in fish production in Vietnam then, this is not necessarily a shift that has worked to the benefit of households in the coastal communities we studied. For most, aquaculture has not generated very high incomes so some are making it a less important aspect of their livelihood portfolio, not dropping it completely but shifting productive efforts to other livelihoods. Meanwhile, economic growth and structural change have created new opportunities for wage employment and self-employment for growing numbers of households. However, human and financial capital are necessary conditions for taking advantage of such opportunities arising from Vietnam's economic development, which raises concerns about growing economic inequality in the country's coastal communities.