Born in the Lemay region of St. Louis, MO, Smith was raised in the neighborhood of Carondelet. Growing up, Smith developed a passion for dancing and performing, which she carried with her well into her days as a student at Cleveland High School. During that time, her advanced abilities landed her complete scholarships to study the craft at both Tulsa University and Kansas University. When Smith graduated high school in 1967, she headed to the University of Missouri and received a degree in elementary education, which she later put to use post-college as a preschool teacher for three years. Meanwhile, Smith continued honing her craft. Her education in dance also extended to tap and ballet, which she learned from Marjorie Mendolia, a former member of the San Carlo Opera Company. She made further inroads into the St. Louis dance community, studying jazz dancing with Raoul Appel, while becoming a dancer with both the St. Louis Civic Ballet and St. Louis Dance Theater.All throughout the 1970s, Smith's post-collegiate career extended to turns supporting herself in a myriad of jobs, including one at a J.C. Penney warehouse, where she indulged a penchant for pranks, and doing reception work at an aerospace defense firm, at which she became "Employee of the Year." But Smith also kept her creative pursuits in sight. She utilized both her comedy and dancing skills, providing some comedic relief with burlesque shows like Will B. Able and his Baggy Pants Revue, and alongside the Mercer Brothers in "Giggles Galore." At one point, Smith had parlayed her versatile dancing skills into a cheerleader gig with the former St. Louis Cardinals football team.By the mid-'80s, Smith was on the road as a touring dancer. During one performance, however, she suffered a knee injury while doing a mid-air split, which permanently sidelined her dancing career. By then, she had taken up residence in Los Angeles and decided to transition into a different facet of the entertainment business - namely acting. Looking to acquaint herself with the process, she took acting classes and by the end of the decade, had made it into the Screen Actors Guild. Still, Smith worried that she was reaching an age where producers might begin overlooking her talents.Through the audition circuit, Smith got to meet various casting directors and one of them ended up hiring her to work in the casting office. In 1992, Smith worked as a casting assistant for Geri Windsor on the USA network thriller "A Taste for Killing" (1992), then over a year later, moved up to casting associate, clocking in four seasons on the frontier drama "Dr. Quinn, Medicine Woman" (CBS, 1993-98). When "Dr. Quinn" left the airwaves in 1998, Smith immediately moved on to casting associate work under casting director Allison Jones, beginning with ABC's "Spin City" (1996-2002) from 2000 to 2002. From 2003-06, She worked solely with Jones on projects ranging from the HBO comedy "Curb Your Enthusiasm" (2000-) and ABC's short-lived "Life as We Know it" (2004-05), to the Disney's family superhero feature, "Sky High" (2005). By the start of 2005, while working with Jones on an American remake of BBC's cult hit "The Office" (2001-03), Smith was asked to do the reads for several plum roles in the pilot by its director, Ken Kwapis. A veritable go-to-performer, she also appeared on a March 2005 episode of the Fox series "Arrested Development" (2003-06), another show for which she was helping to cast. Her readings for "The Office" were so impressive to series producer-developer Gregg Daniels, that he quietly added the role of Phyllis to the series. Jones graciously let her casting associate take the opportunity and Smith transitioned into the series fulltime. Smith also made an unbilled appearance as the mother of "The Office" star Steve Carell in the big screen comedy "The 40-Year-Old Virgin" (2005). After two seasons on NBC's "The Office," Smith graduated from recurring cast member to series regular. Meanwhile, she and her fellow "Office" mates took home the award for Outstanding Performance by an Ensemble in a Comedy Series at the 2007 Screen Actors Guild Awards. Between seasons, Smith built on his increasing exposure by appearing in films including Jeff Garlin's indie romantic comedy "I Want Someone To Eat Cheese With" (2006), Diablo Cody's "Bad Teacher" (2011), and the political satire "Butter" (2011). After "The Office" closed up in 2013, Smith took on a supporting role in the sitcom "Trophy Wife" (ABC 2013-14). She next co-starred opposite Amy Poehler and Bill Hader in the high-profile Pixar animated comedy "Inside Out" (2015) as the personification of the emotion Sadness in the mind of a young girl.