This paper identifies impacts of value chain inclusion on labour from a social sustainability perspective. It focusses on the tasks, livelihoods and subjectivities of Amazonian flood plain peasants (ribeirinhos) who collect açaí for sale to an expanding market. The ‘logic’ of ribeirinho chain inclusion is explored using a combination of labour process and human security indicators. While household income benefits can be significant, gains may be threatened by monoculture trends and local power structures. Human security indicators suggest further caution. Whilst ribeirinhos remain very ‘flexible’ workers, chain engagement entails insecurities, as highlighted by their variable views of collectivity and contradictory positions with respect to sustainability. Sustainable chain prognoses require a deeper understanding of agents' means and of the preferred choices and voice of those working at the beginning of chains.