Over the past several decades, millions of temporary foreign workers have come to the United States through nonimmigrant visa programs. Unfortunately, many guestworkers are exploited, abused, and even trafficked due to systemic program flaws that create imbalances in favor of employers. Anti-trafficking and labor rights advocates, researchers, and policymakers are working creatively and tenaciously to prevent trafficking under nonimmigrant visas, support trafficking survivors, and advance reforms to protect workers and reward good employers. However, their efforts are hampered because they cannot access accurate, up-to-date, and holistic data about those programs. Data transparency will put data that is already collected in the hands of the workers and advocates who need it to combat trafficking. Transparency is a commonsense first step toward eliminating the scourge of human trafficking under U.S. guestworker visas.