Dr. Hadden conducts research on the politics of climate change, with a focus on NGOs and social movements.   Dr. Hadden’s first book — titled Networks in Contention: The Divisive Politics of Global Climate Change — was published by Cambridge University Press in 2015.  It received four book awards from the American Political Science Association and the International Political Science Association. Her second book with Sarah Bush — titled Crowded Out: The Competitive Landscape of Contemporary International NGOs — was published in 2025 and is available in open access from Cambridge University Press. 

Her research has been supported by grants from the National Science Foundation, the National Socio-Environmental Synthesis Center, a Fulbright Fellowship, and others.  She has published in outlets such as Nature Climate Change, British Journal of Political Science, International Studies Quarterly, Global Environmental Politics, Energy Policy, Foreign Affairs, and others. She held an International Affairs Fellowship from the Council on Foreign Relations for the 2015-2016 academic year, supporting work on the Paris Climate Conference in the Office of the Special Envoy for Climate Change at the U.S. Department of State.