Almost forty years ago, noted immigration scholar Jorge A. Bustamante published an article in the "American Journal of Sociology" applying Howard Becker's labeling theory to the phenomenon of deviantizing and stigmatizing the undocumented. While immigration laws and some of the players involved have changed since his article was published, labeling theory remains an ideal tool for analyzing anti-immigrant and pro-immigrant postulates, arguments, and policies. This essay revisits labeling theory, as seen through Bustamante's lens, in order to understand the debates around the undocumented over the past two decades. Three types of "moral entrepreneurs" advocating for and against the undocumented worker are examined: the nativist, the economic, and the humanitarian. An expanded moral entrepreneurship model can illuminate social processes affecting a vulnerable population through the insertion of a moral argument component and in this way may act as a catalyst for positive social change.