This article is a mutual introduction of the science of well-being to philosophy of science and an explanation of how the two disciplines can benefit each other. In the process, I argue that the science of well-being is not helpfully viewed as a social or a natural, but rather as a mixed, science. Hence, its methodology will have to attend to its specific features. I discuss two of its methodological problems: justifying the role of values, and validating measures. I suggest (...) that tackling them calls for developing mid-level rather than high theories of well-being. (shrink)