Cultivating inequality? Regional rubber dynamics and implications for voluntary sustainability programs in Lao PDR

•Natural rubber production was associated with increased economic inequality in Laos from 2007/08 to 2012/13.•Inequality and polarization trends varied regionally.•Increased inequality and polarization were greatest in the South, which is dominated by large-scale concessions.•Voluntary multi-stakeholder programs and government regulation are needed to address rubber’s socioeconomic impacts.•Rubber sustainability programs should address systemic drivers of inequality to maximize benefits and avoid unintended consequences.