The EarthScope Portal is being developed in order to provide a unified, single-point of access to EarthScope data products from USArray, PBO, and SAFOD experiments. The portal will feature basic search and data access capabilities to allow users to discover and access EarthScope data using spatial, temporal, and other metadata- based search conditions. In this presentation, we will describe the features and design of the portal, which is being developed by a team consisting of GEON (Geosciences Network, http://www.geongrid.org), IRIS, UNAVCO, and Stanford. The portal search module invokes Web services developed by IRIS, UNAVCO, and Stanford to search for EarthScope data in the archives at each of these locations. The Web services provide information about all resources (data) that match the specified search conditions. Users will be able to select from the returned data sets, add selected data to a "data cart", and request the selected data to be packaged for download to the user. The initial services being defined are for "station discovery", to find which stations are available for specified spatial and temporal bounds, and "data discovery", to find the data sets that are available from the stations. Users will subsequently be able to choose the specific datasets, which will be assembled in a user "workspace" and available for download. The EarthScope Portal leverages the significant portal development efforts of the GEON Project at the San Diego Supercomputer Center, SDSC (http://portal.geongrid.org), and the development of Web services interfaces at the three data archive facilities. The portal is implemented using the open source GridSphere portal software infrastructure which supports the well-known Java portlet interface, viz. JSR 168 or the Portlet API. It uses a set of "core" portlets that have been developed in GEON for Data Registration, Search, and Workspace Services. We will provide a report on the current state of development of the Portal. A preliminary deployment of the portal software has been done on systems at SDSC; initial design has been done for the StationDiscovery and DataDiscovery services; and IRIS, UNAVCO, and Stanford have begun implementation of early version of the corresponding Web services which will run on servers at their respective locations. An early demonstration of this capability will be provided at the AGU meeting.