Multidimensional modeling requires specialized design techniques. Though a lot has been written about how a data warehouse should be designed, there is no consensus on a design method yet. This paper follows from a wide discussion that took place in Dagstuhl, during the Perspectives Workshop “Data Warehousing at the Crossroads”, and is aimed at outlining some open issues in modeling and design of data warehouses. More precisely, issues regarding conceptual models, logical models, methods for design, interoperability, and design for new architectures and applications are considered. Categories and Subject Descriptors H.4.2 [Information Systems Applications]: Types of Systems—Decision support; H.2.1 [Database Management]: Logical Design General Terms Design Keywords Data warehouse design, multidimensional modeling