Under the stewardship of creator Charles Schulz, the Peanuts comic strip is a kid’s world. The stories of Charlie Brown and his cast of supporting characters are told entirely from their perspectives, with adults very rarely intruding on their adventures or existential conversations. Considering Charlie Brown’s recurrent malaise and social status of "blockhead," a therapist may have been the least Schulz could have done for him.

That never materialized. The reason, according to Schulz, was that grown-ups were simply not needed. Speaking about the kids' lack of parents in 1975, Schulz said:

“I usually say that [adults] do not appear because the daily strip is only an inch and a half high, and they wouldn’t have room to stand up. Actually, they have been left out because they would intrude in a world where they could only be uncomfortable. Adults are not needed in the Peanuts strip. In earlier days I experimented with off-stage voices, but soon abandoned this as it was not only impractical but actually clumsy. Instead, I have developed a cast of off-stage adults who are talked about but never seen or heard.”

In 1997, Schulz elaborated on his no-adults policy, citing concern over ruining the magic of the strip and the jarring juxtaposition of Snoopy and Woodstock behaving like humans around adults:

“Now, we can go [in] any direction with Snoopy. Woodstock, too. It’s absurd to think of this dog and this bird wandering through the woods going on hikes and camping out. So as soon as an adult is in the strip, bang, the whole thing collapses. Because the adults bring everything back to reality. And it just spoils it.”

While not having any adults was the general rule, some still made it into the strip. Aside from occasional off-panel comments in the early 1950s, Schulz drew a pair of adult legs in two 1954 strips set at a golf tournament. In another 1954 strip, two adults can be seen from a distance, though their faces are blurred. Other times, Schulz would depict adults in a more roundabout manner. In a 1964 strip, the reader sees a drawing of an adult composed by Linus. In a 1999 strip, Schulz depicted the Washington Crossing the Delaware painting by artist Emanuel Leutze. Photographs of Dwight D. Eisenhower and World War II correspondent Ernie Pyle have also run in the strip to commemorate D-Day and Veterans Day, respectively.

When Peanuts was adapted for a long-running series of animated specials beginning with 1965’s A Charlie Brown Christmas, adults took on a slightly more prominent role. While they did make occasional appearances, including 2000’s It’s the Pied Piper, Charlie Brown, they’re mostly heard but not seen, communicating in an unintelligible warble. Producer Lee Mendelson asked composer Vince Guaraldi to use a musical instrument as a substitute for their dialogue. Guaraldi used a trombone (“mwa-mwa”) and adults remained relegated to the margins of Peanuts.