[2] Gillespie has edited one anthology, Choice: The Best of Reason[3][4] and is known for his media appearances on outlets such as CNN, Fox News, MSNBC, and HBO's Real Time with Bill Maher, where he advocates for libertarian perspectives.

[7] Under his leadership, Reason expanded its digital and multimedia presence, becoming a leading platform for libertarian analysis and commentary.

Gillespie was born in Brooklyn, New York, and grew up in Monmouth County, New Jersey,[8] where he graduated from Mater Dei High School.

"[16] In 2011, Gillespie published The Declaration of Independents: How Libertarian Politics Can Fix What's Wrong with America with Reason editor-in-chief Matt Welch.

[4] Gillespie is on the board of Ideas Beyond Borders, a nonprofit founded by Faisal Saeed Al Mutar and Melissa Chen.