As Edwin McDowell reported in the New York Times Book Review (8 November 1981), Silverstein "for several years now... has refused interviews and publicity tours, and he even asked his publisher not to give out any biographical information about him." What is known about Silverstein, however, is that he was born in Chicago (Illinois) in 1932, was divorced and had one daughter. Most of what is known about his views and opinions, aside from what may be interpreted from his works, comes from a Publisher's Weekly interview with Jean F. Mercier from 1975. Silverstein discussed the roots of his career in his childhood:
| When I was a kid - 12, 14, around there - I would much rather have been a good baseball player or a hit with the girls. But I couldn't play ball, I couldn't dance... So, I started to draw and to write. I was... lucky that I didn't have anyone to copy, be impressed by. I had developed my own style, I was creating before I knew there was a Thurber, a Benchley, a Price and a Steinberg. I never saw their work till I was around 30.
Source: 1975.02.24 Publisher's Weekly
Silverstein's talents were already well-developed by the time he served in the US armed forces during the 1950s. He was stationed in Japan and Korea, and while in the military, he was a cartoonist for the Pacific edition of the military newspaper, Stars and Stripes. After his stint in the military, Silverstein became a cartoonist for Playboy in 1956. His work for that magazine has resulted in some published collections, such as A Playboy's teevee jeebies and More Playboy's teevee jeebies (Do it yourself dialogue for the Late Late Show).
Silverstein did not begin writing for children until he penned Uncle Shelby's story of Lafcadio, the Lion who shot back, published in 1963. He confided to Mercier:
| I never planned to write or draw for kids. It was Tomi Ungerer, a friend of mine, who insisted... practically dragged me, kicking and screaming, into [editor] Ursula Nordstrom's office. And she convinced me that Tomi was right, I could do children's books.
Source: 1975.02.24 Publisher's Weekly
Lafcadio, the Lion who shot back is the story of a lion who obtains a hunter's gun and practices until he becomes a good enough marksman to join a circus. A Publisher's Weekly (28 October 1963) reviewer called the book "a wild, free-wheeling, slangy tale that most children and many parents will enjoy immensely", and it met with moderate success, as did Silverstein's Uncle Shelby's a giraffe and a half (1964).
But Silverstein achieved fame as a children's writer after the publication of The giving tree in 1964. The book had been rejected by editor William Cole who felt that the book fell between adults' and children's literature and would never sell. In Silverstein's eyes it was a story about two people; one gives and the other takes. Ultimately, both adults and children embraced the book. The story of a tree that gives its shade, fruit, branches, and finally its trunk to make a little boy happy, The giving tree had slow sales at first, but its audience steadily grew. As Richard R. Lingeman reported in the New York Times Book Review (30 April 1978), "Many readers saw a religious symbolism in the altruistic tree; ministers preached sermons on The giving tree; it was discussed in Sunday schools." But feminist critics later saw something else in Silverstein's tale; as Barbara A. Schram noted in Interracial Books for Children (Vol. 5, No. 5, 1974): "By choosing the female pronoun for the all-giving tree and the male pronoun for the all-taking boy, it is clear that the author did indeed have a prototypical master / slave relationship in mind... How frightening that little boys and girls who read The giving tree will encounter this glorification of female selflessness and male selfishness." Nevertheless, the book remains popular with both children and adults.
In the late 1960s Silverstein became also known for being a composer and lyricist of songs, including "A boy named Sue" (sung by Johnny Cash, 1969), "One's on the way", "The unicorn" (sung by the Irish Rovers), "Boa constrictor", "So good to so bad", "Sylvia's mother" (sung by Dr. Hook, 1972), "The great conch train robbery", and "Yes, Mr. Rogers".
Albums of Silverstein's songs recorded by others include Freakin' at the Freaker's Ball [Columbia] (1972), Sloppy seconds [Columbia] (1972), Dr. Hook [Columbia] (1972) and Bobby Bare sings lullabys, legends and lies (The songs of Shel Silverstein) [RCA Victor] (1973).
Albums of original motion picture scores include Ned Kelly [United Artists] (1970), Who is Harry Kellerman and why is he saying those terrible things about me? [Columbia] (1971), in which Silverstein even played a role, Thieves (1977) and Postcards from the edge (1996). Other recordings include Drain my brain [Cadet] (), Dirty feet [Hollis Music] (1968), Shel Silverstein (Songs and stories) [Casablanca] (1978) and The great conch train robbery  (1980).
In 1974 Silverstein published a collection of poems for children called Where the sidewalk ends. Bringing him comparisons to the likes of Dr. Seuss and Edward Lear, Where the sidewalk ends contained humorous efforts such as "Sarah Cynthia Sylvia Stout / would not take the garbage Out", "Dreadful" and "Band-aids". Kay Winters lauded the author's achievement in The Reading Teacher: "With creatures from the never-heard, Ickle Me Pickle Me, Tickle Me too, the Mustn'ts, Hector the Collector and Sarah Cynthia Sylvia Stout (who would not take th garbage out), Silverstein's funny bone seems to function wherever he goes." She further noted that Where the sidewalk ends "is an ideal book for teachers to have handy." The book has proved popular with child readers as well; it continues to sell many copies, as does Silverstein's 1981 follow-up collection of poems, The light in the attic. Publisher's Weekly called the latter book "a big, fat treasure for Silverstein devotees, with trenchant verses expressing high-flown, exhilarating nonsense as well as thoughts unexpectedly sober and even sad."
Silverstein's 1976 picture book, The missing piece, like The giving tree, was subject to varying interpretations. It chronicles the adventures of a circle with a wedge of itself missing, who goes along singing and searching for that missing part. But after the circle finds the right wedge, he decides he was happier on the search - without the missing piece - than he is with it. As Anne Roiphe explained in The New York Times Book Review (2 May 1976), The missing piece can be read in the same way as "the fellow at the singles bar explaining why life is better if you don't commit yourself to anyone for too long - the line goes that too much togetherness turns people into bores - that creativity is preserved by freedom to explore from one relationship to another... This fable can also be interpreted to mean that no one should try to find all the answers, no one should hope to fill all the hopes in themselves, achieve total transcendental harmony or psychic order because a person without a search, loose ends, internal conflicts and external goals becomes too smooth to enjoy or know what's going on. Too much satisfaction blocks exchange with the outside." Silverstein published a sequel, The Missing Piece meets the Big O, in 1981. The latter book is told from the missing piece's point of view; as in the original, the book's protagonist discovers the value of self-sufficiency. A new book for children, Falling up, was published in 1996. Silverstein illustrated his own books with black-and-white line drawings. Being himself a book collector, he took the feel and look - the paper, the type, the binding - of his titles very seriously. He did not allow his books to be published in paperback. But this hasn't hurt his popularity: in the 1990s Silverstein had 14 million copies in print.
Since 1981, Silverstein had concentrated on writing plays for adults. One of his best known, The lady or the tiger show (1981), about a television producer who goes to unbelievable lengths to get his ratings up, has been performed on its own and in a group of one-acts entitled Wild life (1983). Silverstein also collaborated on the screenplay Things change (1988) with playwright David Mamet.
Shel Silverstein died on 10 May 1999 from a heart attack.