Welfarist libertarianism is the view that libertarian institutions promote social welfare more successfully than available alternative institutional arrangements. This chapter surveys the principal welfarist arguments for and against libertarianism. After a brief sketch of the most prominent theories of welfare, I outline the basic welfarist case for libertarianism and consider whether welfarism can provide an adequate defense of rights. Next, I review the central welfarist objections to libertarianism along with libertarian replies, starting with the market’s inability to provide mutually beneficial public goods. I close by examining arguments alleging that an active redistributive and regulatory state outperforms libertarian institutions in promoting the welfare of the poor and protecting people from their own bad choices.