Law and policy on prostitution are being debated and changed in many countries around the world. A number of countries have changed their laws and policies on prostitution in the last seven years (the Netherlands, Germany, Sweden, New Zealand, and South Korea), and several more governments have proposed change in their prostitution laws (the Czech Republic, Hungary, Ghana, Russian Federation). The different state approaches to prostitution – prohibition, regulation, decriminalization, and abolition – will be defined and described. Central to the debate on law and policy on prostitution is the relationship between sex trafficking and prostitution. All four of these approaches have been implemented in at least one country, and in every case advocates of the change in law predicted a decrease in sex trafficking of women and children into the country as an outcome. This paper will describe the impact of change in prostitution law and policy on prostitution and the sex trafficking of women and children in several countries, including the U.S.