In response to domestic and international concern about individuals being exploited for labor or commercial sex, the U.S. Government passed legislation in 2000, creating a new crime of human trafficking and devoting resources to the identification of victims and prosecution of perpetrators. Since that time, all 50 states have passed legislation criminalizing trafficking of persons, yet law enforcement responses to these new legal mandates have been uneven. Recent research suggests police agencies are generally unprepared to identify and respond to human trafficking incidents in local communities and, as a result, relatively few cases have been identified. Using data from medium-to-large municipal police agencies in the United States, this research examines competing explanations for the adoption of responses in the wake of new human trafficking laws. The findings suggest the importance of institutional explanations including organizational experience with change.