Ira Flatow

NPR Science Correspondent, Host of "Science Friday;" Science Media Expert

Mara Liasson

National Political Correspondent for NPR

Steven Squyres

Scientific Investigator, NASA

Drew Houston

Co-Founder & CEO of Dropbox

Tyrese Gibson

R&B Singer, Actor & Author

Vandana Shiva

World-Renowned Environmental Leader

Carmen Wong Ulrich

Personal Finance Expert

Elizabeth Cohen

Senior Correspondent for the CNN Health, Medical, & Wellness Unit

Elizabeth Cohen - CNN news story on baby formula shortage

Tonya Lewis Lee

Author, Producer, Filmmaker & Entrepreneur; Women's Health Activist

Tonya Lewis Lee on the Black maternal mortality crisis

Talib Kweli

Rapper, Emcee, Activist & Entrepreneur

Beth Simone Noveck

Founder & Director of The Governance Lab; Professor & Author of "Solving Public Problems"

Shirin Ebadi

Nobel Peace Prize-Winning Iranian Activist & Lawyer

Ethan Zohn

Winner of "Survivor" Africa, 2x Cancer Survivor, Stem Cell Transplant Recipient, Social Entrepreneur, Philanthropist, Cancer Research Advocate, Former Pro Soccer Player, Sports Broadcaster & TV Personality

Rachel Simmons

Internationally Recognized Educator & Best-Selling Author

Brad Meltzer

Host of History Channel’s "Lost History" & "Brad Meltzer’s Decoded;" New York Times Best-Selling Author

John Zogby

Trendspotter & Leading Pollster

Jon Landau

Academy Award-Winning Producer of Titanic & Avatar

Graham Hill

Founder of Life Edited & TreeHugger.com

Mariane Pearl

Widow of Journalist Daniel Pearl

Bernard Kouchner

Former Minister of Health of France; Founder of Nobel Peace Prize-Winning Médecins Sans Frontières