Marcia Langman is a conservative activist with the Pawnee organization the Society for Family Stability Foundation (SFSF). She is very much against nude art being sponsored by the government, relating it to pornography, and is also against gay marriage.
Marcia is first introduced to the show in "Pawnee Zoo" after Leslie Knope accidentally marries two male penguins. She tells Leslie to either repeal the marriage and denounce gay marriage, or to step down from her position, saying that, "when gays get married, it ruins marriage for the rest of us." Marcia goes on Pawnee Today to discuss Leslie's supposed stance on gay marriage, along with television host Joan Callamezzo. Leslie insists she has not taken a political position, even after Marcia brings up the recent party at The Bulge. Numerous citizens call in on the air and also call for Leslie to resign. Leslie ultimately ends up relocating the penguins to Iowa, where gay marriage is legal.
Marcia returns in "Jerry's Painting" when Jerry's artistic depiction of a nude female centaur that resembles Leslie Knope and a winged baby which resembles Tom Haverford becomes a citywide topic. Marcia insists that the painting be destroyed, or as she quoted, "Burned here first, burned in hell second." After the Pawnee Public Arts Commission calls for the painting to be destroyed, Leslie has Jerry create a duplicate of the painting. He replaces the nude female centaur with a bare chested male centaur, and Leslie convinces Marcia that the original painting has been painted over so it's no longer offensive.
She also appears briefly in Time Capsule, arguing against the inclusion of Twilight in the time capsule.
Marcia appears again in Sex Education, along with her husband Marshall Langman, this time to oppose an initiative to teach sex education to the senior citizens of Pawnee. Citing an abstinence only city ordinance, she forces Leslie to substitute Ann's safe-sex sessions with moralistic preaching about abstinence.