structural:scholar_edition, information:filtering, quality:corruption
Advertising and retail

The characters from the comic have long been licensed for use on merchandise, the success of the comic strip helping to create a market for such items. In 1958, the Hungerford Plastics Corporation created a set of five vinyl dolls of the most famous characters (Charlie Brown, Snoopy, Lucy, Linus, and Schroeder); they expanded this line in 1961 to make the dolls slightly larger and included Sally and Pig-Pen. An early example of the characters appearing in promotional material was strips and illustrations drawn by Schulz for the 1955 instructional booklet for the Kodak Brownie camera, The Brownie Book of Picture Taking. Another early campaign was on behalf of Ford Motor Company; magazine illustrations, brochure illustrations, and animated television spots featuring the characters were used to promote the Ford Falcon from January 1960 into 1964. Schulz credited the Ford campaign as the first time where licensing the characters earned "a lot of money". However, he expressed a dislike of illustrating the adverts, describing it as "hard work" and would have preferred to dedicate equivalent effort to drawing the Sunday format strips.

Some licensing relationships were maintained long-term. Hallmark began printing greetings cards and party goods featuring the characters in 1960. In the late 1960s, Sanrio held the licensing rights in Japan for Snoopy. Sanrio is best known for Hello Kitty and its focus on the kawaii segment of the Japanese market. Beginning in 1985, the characters were made mascots and served as spokespeople for the MetLife insurance company, with the intention to make the business "more friendly and approachable". Schulz justified the licensing relationship with MetLife as necessary to financially support his philanthropic work, although refused to openly describe the exact details of the work he was financing. In 2016, the 31-year licensing relationship with MetLife ended. The relationship resumed in 2023 with Snoopy returning as a mascot for pet insurance.

In 1999, it was estimated that there were 20,000 different new products each year adorning a variety of licensed items, such as: clothing, plush toys of Snoopy, Thermos bottles, lunch boxes, picture frames, and music boxes. The familiarity of the characters also proved lucrative for advertising material in both print and television, appearing on products such as Dolly Madison snack cakes, Chex Mix snacks, Bounty paper towels, Kraft macaroni cheese and A&W Root Beer.

The sheer extent to which the characters are used in licensed material is a subject of criticism against Schulz. Los Angeles Times pointed out that "some critics Schulz was distracted by marketing demands, and his characters had become caricatures of themselves by shilling for Metropolitan Life Insurance, Dolly Madison cupcakes and others." Schulz reasoned that his approach to licensing was in fact modest, stating "our program is built upon characters who are figuratively alive" and "we're not simply stamping these characters out on the sides of products just to sell products" while also adding "Snoopy is so versatile he just seems to be able to fit into any role and it just works. It's not that we're out to clutter the market with products. In fact anyone saying we're overdoing it is way off base because actually we are underdoing it".