Description: The purpose of this guide is to share “proven practices”—good practices with demonstrated effectiveness—that facilitate achievement of improved waste collection, waste management, and reduction of plastic pollution in Southeast Asia. The guide aims to holistically examine aspects of plastic pollution mitigation projects across a spectrum of implementation areas, which are detailed in the proven practice modules and include: stakeholder engagement, capacity building, implementation, social and behavior change, data and evaluation, and financing. Many of the proven practices explained in this guide are applicable to other contexts and geographies; however, each project location will require a customized approach based on various social, political, cultural, and economic factors.