Shin-pei Tsay is the director of Cities and Transportation in the Energy and Climate Program at the Carnegie Endowment for International Peace. Her research focuses on urban and regional planning issues, particularly in relation to transportation, economic development, energy, and climate change policy.

Prior to joining the Carnegie Endowment, Tsay served as the deputy director of Transportation Alternatives, a nationally renowned non-profit focused on transportation issues in New York City; as a founding member of the NYC office for ZGF architects where she was on the sustainability team; the chief operating officer of Project for Public Spaces, an international non-profit; and a strategy consultant with a company serving the Fortune 500. Most recently she contributed to New York City's Street Design Manual, New York City's Active Living Design Guidelines, and New York State's Livable Communities Manual. She also co-founded Planning Corps, an organization that matches urban planners with community-based projects, for which her work will be exhibited in the U.S. Pavilion at the 2013 Venice Biennale for Architecture.

She has been interviewed and quoted by the New York Times, Wall Street Journal, and NPR’s Marketplace, as well as other local and industry publications, and is a sought after speaker. She was a finalist in the international design competition, "Reinventing Grand Army Plaza," for which her work is published in the monograph. Tsay is a LEED accredited professional and also reviews books for the Urban Design Forum's quarterly journal, Urban Design Review.