Tom Ashbrook

Former Host of NPR's "On Point"

Ira Flatow

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

Mara Liasson

National Political Correspondent for NPR

Steven Squyres

Scientific Investigator, NASA

Rose Mapendo

Humanitarian / Activist / Congolese Genocide Survivor

Drew Houston

Co-Founder & CEO of Dropbox

Dick Costolo

Former CEO of Twitter and Co-Founder of Feedburner

Tyrese Gibson

R&B Singer, Actor & Author

Vandana Shiva

World-Renowned Environmental Leader

Lucille O'Neal

Author & Motivator

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"

Dr. Samantha Nutt

Medical Doctor, Award-Winning Humanitarian, Bestselling Author & Founder of War Child USA

Stacey Bess

Award-Winning Educator; Keynote Speaker; Advocate for Homeless Youth

Shirin Ebadi

Nobel Peace Prize-Winning Iranian Activist & Lawyer

Raj Patel

Award-Winning Writer, Food Politics Activist, Filmmaker & Academic

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