Infrastructure has long been a priority in development policy, but there is debate over infrastructure impacts. Whereas economic studies show reductions in poverty, social research has documented growing income inequality. We suggest that a focus on livelihoods permits a bridge between the two literatures by highlighting decisions by households that may capture economic benefits but also yield social inequalities. We therefore take up two questions. First is whether new infrastructure allows households to diversify their livelihoods, where diversity begets resilience and thus affords livelihood sustainability. Second is whether households with more diverse livelihoods exhibit greater increases in livelihood diversity, which would widen livelihood inequalities. We take up the case of the Inter-Oceanic Highway, a trans-boundary infrastructure project in the southwestern Amazon. Findings from a rural household survey for the first question show a strong effect of accessibility on increasing livelihood diversity in areas receiving infrastructure upgrades, an indication that infrastructure fosters household resilience. However, results regarding the second question indicate that households with more diversified livelihoods also exhibit larger increments in diversity, which implies growing livelihood inequality. There remains a need to account for inequalities in livelihood diversity, since less diversified households benefit less from new infrastructure and remain more exposed to risks to their livelihoods.