This limited-enrollment seminar focuses on the development of a working framework for sustainable infrastructure systems. The course will start with a mapping of the different disciplines and fields of knowledge required to deliver sustainable infrastructure projects, to be matched by an analysis of the ecology of agents and organizations active in this field. Then, the environmental, social, and economic aspects of sustainability will be examined as they relate to infrastructure and the urban conditions. Tradeoffs, contradictions, and conjectures will be brought into a retrospective as well as exploratory and speculative formation of an agenda on how to conceive, design, and deliver sustainable infrastructure projects. The course will follow a research seminar structure, with limited lectures; discussion, case studies and guest speakers from academia and the industry will constitute the main body of the course. Student work will be in groups, where through analysis of the specific infrastructure types (transportation, energy, water, waste, information, landscapes, etc) and also by presentations and in-class discussion of individual projects, a framework for sustainable infrastructure will emerge.This research-based seminar will draw from the Zofnass Program for Sustainable Infrastructure at the GSD, and will aim in a cross-disciplinary thinking both within the Graduate School of Design, ranging from the urban planning and landscape scales to the individual building scale; and also to the other Harvard schools, such as Public Health, Government, Business, and Engineering , with the seminar to be advertised for cross-registrations. Non-GSD Harvard faculty, members of the advisory committee of the Zofnass program, will participate in some sessions.