Nongovernmental organizations (NGOs) in the anti-human trafficking movement have proliferated over the past few decades; many of these NGOs have joined coalitions to pool resources and expertise. How do changes in the external political environment or the internal coalition structure impact NGO framing strategy? Framing the fight Against Human Trafficking: Movement Coalitions and Tactical Diffusion uses a unique dataset to analyze the discursive processes of fifteen U.S. anti-trafficking NGOs involved in the Alliance to End Slavery and Trafficking (ATEST) from 2008-2014. This analysis shows that ATEST has targeted the state (contentious politics) and private industry (private politics) to advance its agenda. Sex trafficking has normally been met with tactics from the contentious politics model due to its historical legal connection with prostitution; labor trafficking, conversely, has been approached via the private politics model due to its connection with business. However, the coalition's formal organizational structure has enabled members to learn from each other and apply these models in innovative ways. This study builds theory by showing how learning in social movement coalitions can diffuse tactics and provide new action repertoires for members.