"Só Muda a Moeda" is the result of doctoral research in social anthropology carried out between 2009 and 2013 in Portugal. Analyzing the concepts of trafficking in human beings (THB), especially for the purposes of sexual exploitation, prostitution and sex work, the author searches for their meanings through fieldwork with experts and marginal populations targeted by THB laws: prostitutes and migrants, especially irregular migrants. The result is an unexpected reflection on gender logic, migration regulation mechanisms, legality and illegality in relation to access to territories, resources and citizenship. The fact that this happens above all to women, transgender people and sex workers is certainly cause for anthropological inquiry.