This report assesses the most powerful Syrian armed opposition groups on the battlefield as of March 16, 2016 and details key aspects of each group, including the group’s leadership and perspective on Jabhat al-Nusra, that will need to inform American strategies in Syria. The armed groups examined in this report include groups that currently receive American support, groups that are potential American allies, and groups allied to al Qaeda in Syria that stand to gain additional power in the next year.