External aid can facilitate or hinder long-term peace and development. In light of the massive on-going relief effort in Haiti, it is critical to minimize harmful impacts and maximize positive impacts. Aid can worsen polarization and violence, often inadvertently, or can have positive effects on conflict and social cohesion. Although Haiti has not experienced a civil war or a war with neighbors, nevertheless, it must be considered as an active conflict zone, in which the level of violence has been high for decades. We highlight here a number of lessons drawn from several initiatives led by CDA Collaborative Learning Projects over the last 20 years, in partnership with thousands of colleagues in humanitarian, development, and peacebuilding organizations. As we continue to learn more about the current context in Haiti, this document will be continually updated— please see www.cdainc.com for the most recent version.