Adequate conservation of biodiversity on private land remains elusive due, in part, to a failure to understand the personal circumstances and social characteristics of private landholders. Our aim was to identify those personal and social dimensions of landholders that might contribute to improved conservation policy and program design and, thereby, participation in private land conservation. We tested whether personal circumstances of landholders (e.g., lifestyle and wellbeing, information and knowledge, financial security) and social characteristics (e.g., attitudes, norms, and trust) would be important predictors of landholders' capacity and willingness to participate in biodiversity conservation programs. Forty-five participants and twenty-nine non-participants of biodiversity conservation programs in north Queensland, Australia, were surveyed to: 1) examine differences between their personal circumstances and social characteristics that may influence participation; and 2) explore whether personal circumstances and social characteristics were influenced by participation. The results revealed that, compared to participants, non-participants in conservation programs had significantly different personal circumstances and social characteristics for four of eight measured variables. Compared to participants, non-participants demonstrated a reduced capacity and willingness to participate in conservation programs. Participation did not appear to have a strong influence on participants' personal circumstances or social characteristics, and when social norms supported conservation, programs did not demonstrate additionality. Conservation policies that maintain or improve landholders' personal circumstances and that promote pro-environmental norms may result in increased participation and thereby conservation outcomes.