Why do the networks make a critic’s life so easy? Calling a sitcom “Less Than Perfect” (8:30 p.m., ABC) all but invites cheap jabs about its shortcomings. And “Less Than Perfect” has its share. But Sara Rue’s funny, charming and consistently endearing performance as a plus-sized temp in a chic office environment more than compensates for the series’ many imperfections.

Claude (Rue) is a big girl with a heart of gold who toils as a floating temp at the fictional GBN network. She befriends Ramona (Sherri Shepherd) and Owen (Andy Dick) from the lowly fourth floor. Well accustomed to their nerd status, the trio find solace in fantasy romances, free candy and overeating.

Claude’s life changes when she is assigned to the Olympian heights of the 22nd floor as the assistant to news anchor Will Butler (Eric Roberts). He takes an immediate liking to Claude’s cheerful competence.

Much like the 1989 movie “Working Girl,” “Perfect” demands that the audience root for the office Cinderella. And like “Hairspray,” its hefty heroine displays surprising depths of spunk, cunning and ambition. Unfortunately, too much of this comedy unfolds with the cartoon superficiality of “The Drew Carey Show.”

Viewers who spent last week rewatching “The Civil War” might turn their attention to “The Rise and Fall of Jim Crow” (9 p.m., PBS). Richard Roundtree narrates this documentary history of the savage enforcement of racial segregation in America from the end of Reconstruction to the beginnings of the modern Civil Rights movement. The series will continue Tuesdays through Oct. 22.

Tonight’s other highlights

Major league baseball playoffs (7 p.m., Fox).

“NOVA” (7 p.m., PBS) enters its 29th season with an examination of theories about the origins of caves.

A teen faces adult sentencing for a heinous crime on “The Guardian” (8 p.m., CBS).

Amy faces Maxine in court on the fourth-season premiere of “Judging Amy” (9 p.m., CBS).

Scheduled on “Dateline” (9 p.m., NBC): A teen party binge results in two fatalities.

Anthrax poisoning on “NYPD Blue” (9 p.m., ABC).

Series notes

Questions of faith muddle military discipline on “JAG” (7 p.m., CBS) On back-to-back episodes of “The In-Laws” (NBC), Matt and Alex need a new bed (7 p.m.), a romantic evening ruined (7:30 p.m.) Bridget gets a trendy job on “8 Simple Rules” (7 p.m., ABC) Buffy joins school staff on “Buffy the Vampire Slayer” (7 p.m., UPN) Meddling leads to a fight between Rory and her father on “Gilmore Girls” (7 p.m., WB) Cheryl hides Jim’s gadget on the second-season premiere of “According to Jim” (7:30 p.m., ABC).

The Cranes take a stand on “Frasier” (8 p.m., NBC) Multitasking madness on “Life with Bonnie” (8 p.m., ABC) A teen is swallowed up by the club scene on “Haunted” (8 p.m., UPN) Lex marries an older woman on “Smallville” (8 p.m., WB) A gym dandy on “Hidden Hills” (8:30 p.m., NBC).

Late night

David Schwimmer and Avril Lavigne appear on “Late Show with David Letterman” (10:35 p.m., CBS) Jay Leno welcomes Reese Witherspoon, Zach Braff and Lifehouse on “The Tonight Show” (10:35 p.m., NBC). Look for Anthony Hopkins, David Grier and Naked Trucker on “Late Night with Conan O’Brien” (11:35 p.m., NBC).