To improve understanding by both policy-makers and practitioners of effective ways to pursue urban sustainability, I will investigate exemplary “green buildings” in the commercial/institutional sector. Despite major obstacles in both Japan and the United States, certain buildings have achieved drastically reduced environmental impacts while maintaining mainstream functioning. How have they done it? The collaboration I propose with Professor Hiroto Takaguchi of Waseda University will develop detailed comparative information about these success stories through exploratory case studies. We will proceed in ways that are new to Japanese and U.S. analysis, by highlighting the inner workings of the design process and identifying the explicit and tacit lessons being absorbed by the design professions about the pursuit of sustainability. Other sources will support a pilot round of three case studies from the Pacific Northwest of the US during 2008-09. I seek Abe Fellowship support during 2009-2011 for nine more cases developed over two three-month periods in Japan and one in the Northeast US, and for two months of writing and dissemination. Given the existence of individual sustainable successes, the crucial questions now for policy and practice are how improved building performance can spread. The present research aims squarely at this, by investigating the design process. It is there, alongside powerful competing values such as function, risk avoidance, and finance that sustainability does or does not find expression in a building. We will seek organizational and professional learning—ways good practices get recognized, carried forward, and absorbed by the profession at large. This is the key to progress toward sustainable results. Understanding it is vital to formulation of effective incentives, regulations, training schemes, and other instruments of policy in this area. This research will make a substantial addition to information flow (now low in this area) between Japan and the US, and will bring forward contrasts which help each country’s professionals see more clearly what they take for granted. One key example concerns systems for rating sustainable achievement. The US LEED system and Japan’s CASBEE have significant similarities, but their origins, intent, frame and implementation differ in many important and potentially instructive ways. The primary materials will be design documentation and focussed interviews with principal participants. Our theoretical frame takes Schön’s concept of “reflective practice” from individual to group work. Designing is a stream of partial actions on a problem situation, each followed by reflective deliberation. Our protocol builds on the US High Performance Buildings Database, adding a substantial component which traces action-reflection cycles for each case. We envisage both written and interactive products. An international workshop (under separate funding) in summer 2011 will bring together people from all the cases to consider our findings on what the professions are learning about sustainable design. Final project profiles for US and Japanese design databases will follow, as well as articles for peer-reviewed journals that reach both academic and professional audiences.