Nongovernmental organizations (NGOs) in the anti–human trafficking movement have proliferated over the past few decades, each focusing on different aspects of the problem. Many of these NGOs have joined coalitions to pool resources and expertise. What are the messages that NGOs use to define and prescribe solutions to the human trafficking issue? How do changes in the external political environment or the internal coalition structure impact NGO framing strategy? This book uses a unique dataset to illustrate and analyze the discursive processes of NGOs over three distinct time periods: 2008–2010, 2011–2012, and 2013–2014. The data was gathered from public documents and supplemented by interviews from fifteen US anti-trafficking NGOs involved in the Alliance to End Slavery and Trafficking (ATEST). This analysis shows that the ATEST coalition has targeted the state (contentious politics) and private industry (private politics) to advance its antihuman trafficking agenda. Sex trafficking has normally been met with tactics from the contentious politics model due to its historical legal connection with prostitution; labor trafficking, on the other hand, has been approached via the private politics model due to its connection with business. However, due to the coalition’s formal organizational structure, members have been able to learn from each other and adopt tactics normally reserved for certain types of targets in new ways, such as using contentious political strategies for labor trafficking and vice versa. This study builds theory by showing how coalition learning in social movements across time periods can diffuse tactics and provide new action repertoires for coalition members.