This book argues that there is nothing distinctively objectionable about paternalism. According to the pro-paternalist view it defends, it is permissible to intervene in a person’s choices or behavior whenever doing so would serve that person’s best interest without wronging anyone else. Many moral and political philosophers reject this view. Some hold that paternalistic intervention is insulting, or that it imposes values on people, or that it violates rights to autonomy. Others follow J. S. Mill in arguing that paternalism is likely to be counterproductive. The book sets out several different versions of these objections, arguing that each fails to refute the core pro-paternalist claim. Moreover, it shows that common anti-paternalist views are subject to a powerful internal critique: they cannot easily accommodate the widely held view that it is generally permissible to intervene on behalf of ill-informed or impaired decision-makers. Although the book’s central aim is to defend a moral principle, it considers several cases to indicate how the principle can be fruitfully applied.