By KATHERINE ROSMAN

When “Saturday Night Live” hosts and cast members stare into the camera, hoping to utter their lines with perfect comedic timing on live television, they are focused on one thing only: the cardboard cue cards held up by Wally Feresten.

“Wally is a character in every sketch, you just don’t see him,” says Alec Baldwin, a 16-time SNL host who has also worked with Mr. Feresten on live episodes of “30 Rock.”

For 22 years Mr. Feresten has been perched next to the live-telecast’s camera, in a wide-legged athletic stance, holding at shoulder height white 14-x-22-inch poster-board cards hand-printed with lines for the performers. Attuned to the rhythms of each actor, Mr. Feresten lifts the cards and drops them into the hands of an assistant. He never looks away from the performer.

“If you can see Wally and his cards you know you’re not going to die,” says NBC Nightly News anchor Brian Williams, who once hosted SNL.

Mr. Feresten, 47 years old, is one of the rare cue card guys left on the job. His business, which employs 15, is enjoying a surprising boom at a time when many thought the gig would have gone the way of the telegraph operator. Teleprompters can offer a less-expensive option, and few in Hollywood expected the traditions of live TV to continue as productions get ever glossier.

In large measure, Mr. Feresten owes his current success to the popularity of the comedy genre—especially sketch-driven programs like SNL that don’t allow for much rehearsal time and often rely on guests who aren’t trained as actors.

Particularly, Mr. Feresten has benefited from the many SNL alumni who now have their own TV shows. He also hoists cards for reality TV programs. Among his customers: late-night stars Jimmy Fallon (who was an SNL cast member) and Conan O’Brien (formerly an SNL writer). SNL veteran Tina Fey, who created and stars in “30 Rock,” relies on Mr. Feresten’s cards when the show airs live episodes. Donald Trump, who has hosted SNL, also calls upon Mr. Feresten when his “Celebrity Apprentice” show goes live.

Executive producer Lorne Michaels launched SNL in 1975 with a mandate to reconnect to the grit of live television, which, in turn, pays homage to the stage. Cue cards were a part of that philosophy.

Their continued use isn’t about hewing to nostalgia. Even though most teleprompters are overseen by a human, the operator usually sits some distance from the stage and the performers. Mr. Feresten often rehearses extensively with hosts and cast members, which helps him to better anticipate their rhythms and act on the fly.

Over the years, there have been a few snafus: Last-minute edits didn’t make it onto the cards, the boards have gotten stuck together. But the system is pretty reliable, says Mr. Michaels. “In the history of the show we’ve only had to shoot the cue-card guy twice.”

Mr. Fallon, a cue-card devotee, had to rely on teleprompters when he hosted the Emmys in 2010. He hated the prompter, which he says trains the eye directly into the lens of the camera. Cue cards are usually held just above the camera and connect the sight line to the audience, Mr. Fallon says. “Cue cards make the performance so much warmer,” he says.

Newer comedy productions like “The Colbert Report” don’t use cue cards. And there is further attrition: A few months ago, late-night host Jimmy Kimmel replaced his cue-card team in favor of a teleprompter.

A spokeswoman for Mr. Kimmel declined to comment.

Mr. Feresten got his break in 1990 when his brother, then a receptionist on the show, landed him an interview. “I went to school for writing for TV, and that’s what I do,” says Mr. Feresten, of Livingston, N.J.

At first, his handwriting was so illegible it took weeks for any of his cards to be used on the live show. “When you write, you move your fingers. But when you do cue cards, you draw, which means you move your hands,” he says.

The decidedly low-tech cue-card operation takes place backstage, directly beneath the audience seats at SNL’s famous Studio 8H at 30 Rockefeller Plaza. Amid wigs, ladders and cans of paint are the four slabs of plywood upon which the show’s script gets written and rewritten on the cards by metal markers with felt tips. When the writers want to change a line, Mr. Feresten covers his letters with white masking tape and writes in the new jokes.

A few weeks ago, minutes before a rehearsal for that evening’s upcoming “Saturday Night Live Weekend Update Thursday,” Mr. Feresten checked the work of his team. He was looking for inconsistencies: every “E” must be written with straight lines, a “G” must have a discernible horizontal line. “Everyone does Zs different,” he said.

Wally Feresten

For the Thursday prime-time special, which aired on Sept. 27, Mr. Feresten had called in guys like Fred Gosker, 40, who has worked under him on and off since 1998. Pete Levin, 38, started a few years later. They don’t share pens because each writer’s hand tends to morph the shape of the felt differently. “People are very protective of their tips,” Mr. Levin said.

About three hours before the live 8 p.m. show, writers and producers dropped off “dirty” scripts that had been edited and required changes to the cards.

“Nah, I don’t get nervous,” Mr. Feresten said.

As it drew closer to airtime, the intensity built. At 7:48, head writer and “Weekend Update” anchor Seth Meyers and a few others hovered over Kyle Orozovich, who was in charge of the cards for a satirical newscast sketch. Mr. Meyers wanted a line cut. Mr. Orozovich taped over the letters.

At 7:52, Kenan Thompson was rehearsing and asked for a bolder period to mark the end of a joke lampooning Princeton professor Dr. Cornel West. The cue-card shuffle continued.

The night of the production, no one noticeably missed a cue or flubbed a line. New cast member Cecily Strong delivered a hilarious turn as a party girl who speaks nonsensically about politics. Fred Armisen drew chuckles depicting Iranian President Mahmoud Ahmadinejad. When Mr. Meyers suggested that “The Casual Vacancy,” the new adult book by J.K. Rowling, might be better with a racy, Harry Potter-esque title (“Hagrid: Nights”), Mr. Feresten suppressed a guffaw.

“You know a joke has landed when you see Wally laugh,” Mr. Baldwin said.

Write to Katherine Rosman at katherine.rosman@wsj.com

A version of this article appeared October 20, 2012, on page A1 in the U.S. edition of The Wall Street Journal, with the headline: Live, From New York…It’s All Eyes On the Cue-Card Guy.