This presentation describes the Washington Families Fund Systems Initiative as an example of how Debra Rog (Westat) and her associates are designing an evaluation of a complex systems initiative funded by the Gates Foundation. The initiative is designed as a comprehensive intervention to enhance systems' ability to end homelessness for families in the State of Washington, USA. This presentation provides an overview of its purposes, research questions, context considerations for the design, process steps for developing the design, and the design and methods. Rog also presents the challenges the evaluation team will face as they move forward with this 5 year, $60 million study.#QuantitativeMethods-TheoryandDesign #SystemsinEvaluation #2010Conference #Cluster,Multi-SiteandMulti-LevelEval #ProgramTheoryandTheoryDrivenEvaluation