Government regulations have created new markets for non-timber forest products such as tropical forest seeds for ecological restoration and agroforestry in Brazil. This paper examines whether and how participation in the seed market has affected assets that will shape households’ ability to pursue new livelihood opportunities. These impacts may vary across different dimensions of capital and among sociocultural groups. Impacts were characterized through semi-structured interviews following the sustainable livelihoods approach; 40 producers in the Xingu Seed Network, from settler farmer, urban and indigenous groups, were interviewed. The groups differed in perceptions of impacts on their natural, social and human capital, which could be related to the sociocultural background and vulnerability context of each group. Communities that were already organized were most likely to strengthen their social capital through participation. Cash income earned from sale of seeds was correlated with household-reported gains in financial capital, but not correlated with changes in other dimensions of capital. Contrary to expectations, sociocultural groups less integrated with the market achieved better livelihood outcomes through participation in the seed market.