The Western North American Volcanic and Intrusive Rock Database (NAVDAT— http://navdat.geo.ku.edu and http://navdat.geongrid.org ) is a relational database that serves as a repository for chemical and age data for igneous rocks in this region and allows, for the first time, the voluminous, high-quality, igneous rock data generated over the past thirty years to be integrated into time-space-composition models of western North American igneous activity. As in other continental regions, the analysis of geochemical, geochronological, and geospatial data from igneous rocks has played a critical role in the understanding of the tectonic evolution of western North America. However, the seminal, regional-scale studies of the tectonic evolution of this region remain primarily those undertaken in the 1970s, prior to the explosion in the number of high-quality chemical and isotopic studies of North American igneous rocks that occurred during subsequent decades. There has been little concerted effort to integrate these new data into regional tectonic models of western North America, due in large part to the lack of a unified, high-quality database for igneous rocks in this region. As a result, the potential that these data have for providing new fundamental insights into the tectonic evolution of the continent remains largely untapped. The NAVDAT effort is designed to remedy this situation. At its core, NAVDAT is a Web-accessible petrologic database with a schema compatible with existing petrologic databases (GEOROC, PetDB), but with an emphasis on a structure that will easily allow these data to be queried and manipulated as functions of age, composition, and geographic position. The NAVDAT user interface includes a number of advanced query options including both graphical and map-plotting analysis tools as well as close linking between data and reference information for the source of the data. NAVDAT allows investigations of continent-scale patterns in magmatism and provides the means to address how local variations in the age, composition, and location of igneous rocks fit into a regional context. The latter ability will produce more thorough and rigorous assessments of the relationships between volcanism and lithospheric deformation, including continental mantle delamination, the controls of subducted slab orientation on space-time-composition patterns of magmatism, and the role of mantle plumes in continental evolution. NAVDAT also will provide basic information on volcanic hazards and geothermal resources in western North America. The overall goal is for NAVDAT to become a rich data tool, an important part of the national geoinformatics effort, and a functioning component of an overall national geoscience cyberinfrastructure.