The Stockholm Environment Institute (SEI) is an international research organization focusing on the issue of sustainable development.
SEI's US center is a research affiliate of Tufts University in Massachusetts and also has offices in Davis, California, and Seattle, Washington.
It conducts a diverse programme focusing on the social, technological and institutional requirements for a transition to sustainability.
In addition to providing policy-relevant analyses, the Center works to build capacity in developing countries for integrated sustainability planning through training and collaboration on projects.
Its decision support tools are widely used: LEAP for energy planning and climate change mitigation, WEAP for water resources planning and PoleStar for evaluating sustainable development strategies.