Cecily Strong

Strong was born in Springfield, Illinois, and was raised in Oak Park, an inner ring suburb of Chicago. She is the daughter of Penelope and William "Bill" Strong, who worked as an Associated Press bureau chief and as of 2013 ran his own public relations firm. Penny Legler Strong is a nurse practitioner, having worked extensively at area hospitals. Strong's parents are divorced. Strong grew up adoring SNL as a child, reenacting sketches with her friend and watching old SNL commercials on VHS. "I had a tape of the best commercials, and I wore it out, every day." She has stated that she was inspired by Phil Hartman.

In a 2021 interview with Terry Gross on the National Public Radio program Fresh Air, Strong said that because her uncle is a Broadway producer, as a child she often was able to attend Broadway shows and sometimes go back stage to meet their casts.

She attended Oak Park and River Forest High School until her sophomore year, when she was expelled for bringing marijuana to school. She then attended a private Catholic school until transferring for her senior year to the Chicago Academy for the Arts, where she graduated in 2002. She then studied acting at California Institute of the Arts (CalArts), graduating in 2006 with a BFA in theatre. After graduating, Strong returned to Chicago where she studied at the Second City Conservatory and iO Chicago.Strong performed regularly at The Second City and iO Chicago. Strong performed on a cruise ship with other Second City members for four months. She appeared at the Chicago Sketch Fest, Chicago Just for Laughs, the New York Sketchfest, the Edinburgh Fringe Festival, the Goodman Theater, the Bailiwick Theater, the Mercury Theater, and with the all-female improv troupe Virgin Daiquiri.