This paper analyzes the recent growth of janitorial unionism in LA against the background of the previous history of unionism's rise and decline in the city's building service industry, asking how and why the Justice for Janitors campaign succeeded in LA, and whether its success will last. This case study indicates the continuing relevance of questions about how poor immigrant workers are able to build successful and enduring organizations and about the relationship between immigrant workers and the rise and decline of unions. It concludes that , on one hand, the immigrant presence was neither a necessary nor sufficient condition of success. On the other hand, in this specific case, the JfJ campaign was probably better off with the immigrants than without them.