Over the past decade mixed-use real estate has received significant attention amongst real estate practitioners including both developers and city/ regional planners. This attention is understandable especially in light of renewed interest in urban revitalization and sustainable real estate development. Unfortunately, little empirical research has been conducted to identify the critical success factors for mixed-use development. This paper addresses this void and explores some fundamental questions surrounding when, why, and where mixed-use development is viable. It begins with an extensive literature review to help identify issues surrounding mixed-use development. It then explores some ''lessons learned'' in mixed-use development in Seattle where such projects have been encouraged by policy makers and other constituencies.