The question of intergenerational obligation can be framed in multiple ways. Here, we use the idea of bargains to think about how those of us in the present relate to both the past and the future. To understand this approach assumptions behind the idea of intergenerational bargains are posited, three potential ontologies for intergenerational thinking are explored, and principles that might be applied to intergenerational obligations are considered. Finally, an ethic for intergenerational obligation is proposed. The idea of intergenerational bargains reveals common frameworks among futures studies, ecological economics, and sustainability science. (C) 2013 Elsevier Ltd. All rights reserved.