I compare Mill's and Sen's accounts of the value of opportunity, focusing on a tension between two ideas they both uphold: that individual freedom is an important component of well-being, and that, because desires can be adaptive, actual desire is not always a good indicator of what will give well-being. The two writers' responses to this tension reflect different understandings of the relationship between freedom and desire. Sen links an individual's well-being to her freedom to choose what she has reason to desire, and looks to a democratic political process for a collective judgement about what it is rational to desire. Mill links the individual's well-being to her freedom to act on her own desires, whatever they may be, within the constraints imposed by a fair initial distribution of resources. He sees no need for collective judgement about what is ultimately valuable in human life. I side with Mill.