Integrated climate assessment is being implemented in the southwestern U.S. as an ongoing process to improve climate awareness, change scientific research on climate, build effective research-applications partnerships around climate and hydrologic variability and change, and sustain those partnerships. In 1998 a four-year pilot integrated science and assessment project focusing on climate variability and vulnerability was initiated, with the specific aims of assessing and improving climate information, its use by regional stakeholders, and the level of understanding of climate vulnerability in the region. A secondary aim was to develop methods for integrated climate assessment as a continuing, ongoing process. The Climate Assessment for the Southwest (CLIMAS) project. CLIMAS was designed to be a highly integrated, long-term process rather than a study culminating in a single product, distinguishing it from national and regional climate assessments done under the U.S. Global Change Research Program. As a process, integrated climate assessment involves building effective research-applications partnerships around regional climate issues and impacts. Interannual variability in seasonal precipitation, particularly winter snowpack, is a central issue that affects essentially all regional stakeholders. Important indicators of success of the regional assessment are an increased demand for climate information, reductions in vulnerability to climate and hydrologic variability and change, a science agenda that is responsive to stakeholder needs, assessment team integration, and quality, frequent researcher-stakeholder interactions. The real key to making integrated climate assessment a high-impact activity in the region is healthy stakeholder-researcher collaboration, which requires a sustained commitment of resources, the flexibility to respond to needs for new climate information, and a continuing effort to improve climate information and its use in the region.