This document discusses GIZ's experiences with scaling up development cooperation projects. It outlines a two-phase process undertaken by GIZ to integrate scaling up into their planning and evaluation processes. Phase I involved analyzing best practices and updating guidance documents. Phase II includes strategically evaluating projects and learning events. The document also presents lessons learned on success factors for scaling up, including having a long-term vision, stakeholder ownership, a multi-level approach, effective evaluation of pilots, standards, scaling up structures, communication, and sufficient time and budget. Examples from GIZ water and coastal management projects in Kenya and Vietnam demonstrate approaches to horizontal and vertical scaling up.