To make a Tequila Mockingbird, chill your martini glass and cocktail shaker in the freezer. After half an hour, remove the shaker,  throw in a handful of ice, one and a half ounces of tequila, three quarters of an ounce creme de menthe, and the juice of one lime. Shake vigorously, pour into a chilled glass, and garnish with a lime. Best enjoyed on an evening when it's warm enough to linger on a veranda, but not so hot that ladies are reduced, as Alabama-born author Harper Lee so memorably described, to "soft teacakes with frostings of sweat and sweet talcum."

To Kill a Mockingbird has inspired odder and greater things than the combination of creme de menthe and tequila. July 11, 2010, marked the fiftieth anniversary of Lee's venerated, controversial, and unavoidable book. Celebrations were everywhere. Special readings and panel discussions took place in locales from Vermont to Alabama to Washington, the 1962 movie starring Gregory Peck in his Oscar-winning role was shown in numerous theaters and libraries across the country, and a bookstore in Santa Cruz, California, hosted a reenactment of the famous courtroom scene. Not even the satirical paper The Onion could resist Mockingbird mania with this spoof headline: "Senate Unable to Get Enough Republican Votes to Honor 'To Kill a Mockingbird.'" Not everyone, however, was extolling Mockingbird's praises. In a June 24, 2010, Wall Street Journal article, "What 'To Kill a Mockingbird' Isn't," journalist Allen Barra kicked Harper Lee out of the canon of great Southern writers. He called Atticus a "repository of cracker-barrel epigrams" and the book as a whole "a sugar-coated myth of Alabama's past that millions have come to accept." Though Barra argued that Mockingbird's "bloodless liberal humanism is sadly dated," last summer's celebrations showed how great a hold it has on readers' memories and their hearts.

Now that the anniversary hoopla has subsided, will this classic that was never meant to be a blockbuster--or a children's book, for that matter--be quietly retired? No. If anything, the fiftieth anniversary reminds us how this book has become so much more than a book. It has generated not just a cocktail but song lyrics, band names, and children's and dogs' names, and myriad young adult books have been inspired by its power. Mockingbird has become a part of the public subconscious, a literary and a cultural touchstone.

To attend high school in the United States is to be required to read Mockingbird. First published in 1960, this novel shocked its debut author and her publisher when it won the Pulitzer Prize and became a best seller. Since then, Mockingbird has sold nearly one million copies a year, and for the past five years has been the second-best-selling backlist title in the country. (Eat your hearts out, Stephenie Meyer and J. K. Rowling.) But how did Mockingbird become a book for youth? Is it because the narrator, Scout, is a young tomboy? Or is it because the novel is both a bildungsroman and a suspenseful courtroom drama? Or was Mockingbird eventually labeled a children's book simply because Flannery O'Connor mused, "It's interesting that all the folks that are buying it don't know they are reading a children's book"? Given Mockingbird's cultural permeation and multigenerational readership, it appears to be a true example of a "book for all ages."

Mockingbird's hold on grown-up minds is certainly evident in the many pop-culture allusions, both obvious and subtle, to Lee's only book. Celebrity magazine readers are probably aware that Demi Moore and Bruce Willis named their daughter Scout after Lee's precocious protagonist. Watchers of the television show Gilmore Girls probably caught the literary reference when Rory says that "every town needs as many Boo Radleys as they can get." And Simpsons viewers young and old undoubtedly laughed when Homer complained about reading: "Books are useless! I only ever read one book, To Kill a Mockingbird, and it gave me absolutely no insight on how to kill mockingbirds! Sure it taught me not to judge a man by the color of his skin... but what good does that do me?"

Mockingbird has also entered the twitterverse via Twitterature: The World's Greatest Books in Twenty Tweets or Less by Alexander Aciman and Emmett Rensin. Aciman and Rensin have Scout narrate as @BooScout in a voice condensed to short, often snarky observations. Here's @BooScout's response to Atticus's advice that to understand a person you must put yourself in his shoes: "Why does Dad say such LAME shit? I don't want to walk a mile in ANYONE else's shoes. Toe jam, nail fungus, athlete's foot anybody? Gosh." High literature Twitterature is not, but anyone who has studied Mockingbird with a long-winded lecturer will appreciate @BooScout's humor and brevity: "Went to the trial. Tom seems innocent. Also, it occurs that our town is full of racists. Perhaps only the eyes of a child can see the truth."

Beyond pop culture, Mockingbird has long provided the legal arena with both inspiration and fodder for discussion. Atticus's courtroom defense of Tom Robinson, a black man accused of raping a white woman, is the subject of law school classes and law review articles. Would Atticus's argument that Tom physically couldn't have harmed Mayella Ewell hold water in a contemporary courtroom? Does Atticus deserve our veneration? In his August 10, 2009, New Yorker article "The Courthouse Ring," Malcolm Gladwell takes Atticus to task for his legal performance. Gladwell argues that instead of challenging the racist status quo, Atticus simply encourages jurors "to swap one of their prejudices for another." He also finds Atticus's decision to have Scout lie about what actually happened the night Bob Ewell attacked her and her brother Jem problematic: "Understand what? That her father and the Sheriff have decided to obstruct justice in the name of saving their beloved neighbor the burden of angel-food cake?" Whether Atticus is a brilliant attorney or a courtroom wimp, the fact that Gladwell and legal scholars are even debating his aptitude with the seriousness they might read Supreme Court decisions speaks of Mockingbird's clout.

Like its impact on pop culture, Mockingbird's presence in literature is a combination of overt tributes and almost subconscious allusions. In Scout, Atticus & Boo: A Celebration of Fifty Years of To Kill a Mockingbird (2010), author Mary McDonagh Murphy interviews writers, journalists, and artists from Oprah Winfrey to Tom Brokaw about how Mockingbird affected their lives. Her interviews with authors including James Patterson, Adriana Trigiani, and Lizzie Skurnick exemplify how this classic, though often read in childhood, can have a lasting hold on writers. Patterson loved it because he identified with Jem and "the suspense was unusual in terms of books that I had read at that point, books that ... had really powerful drama which really did hook you. Obviously I try to do [that] with my books." Skurnick, author of Shelf Discovery: The Teen Classics We Never Stopped Reading, recalls Scout being more fascinating than the "grand themes of justice" in the second half of the book. Everyone interviewed, regardless of vocation, has a story about how Mockingbird touched him or her in a memorable way.

Young adult books such as Jan Marino's 1997 novel Searching for Atticus and Loretta Ellsworth's 2007 In Search of Mockingbird are unabashed love letters to Mockingbird and maybe even Harper Lee herself. Both books feature teenage girls who set out on quests of self-discovery with Mockingbird as their inspiration. In Atticus, Tessa Ramsey tries to reconnect with her surgeon father who has returned from the Vietnam War, while in In Search of Mockingbird Erin runs away from Minnesota to find the reclusive author of her favorite book. Also Known as Harper (2009) by Ann Haywood Leal, National Book Award winner Mockingbird (2010) by Kathryn Erskine, and The Mockingbirds (2010) by Daisy Whitney pay homage to Harper Lee, with varying degrees of genuflection and success.The impact of To Kill a Mockingbird on a text is not always apparent from the title. Sometimes the novel is used in a story as a character litmus test: if a protagonist is reading it and loves it, readers know he or she is a good person--extra points if the copy is dog-eared and not required homework reading. In a similar vein, though Atticus might not be named in a text, it is hard not to think of him in any middle-grade or young adult novel with a courtroom setting. (Monster by Walter Dean Myers and John Grisham's foray into children's books, Theodore Boone: Kid Lawyer, come to mind.)

It's even harder, if not impossible, to see words closely resembling mockingbird on a page and not think of Lee's work. Suzanne Collins, whether intentionally or not, recalls To Kill a Mockingbird with her mockingjay creature in the Hunger Games trilogy. In the final book of the series, Mockingjay, Collins's protagonist Katniss describes a mockingjay, a combination of a (fictional) jabberjay and a mockingbird, as "the symbol of the revolution" and goes on to explain why she must represent the mockingjay herself and "become the actual leader, the face, the voice, the embodiment of the revolution." Katniss's understanding of the emblematic importance of the mockingjay brings to mind Scout's discussion with Miss Maudie Atkinson about why she should never shoot a mockingbird: "Mockingbirds don't do one thing but make music for us to enjoy. They don't eat up people's gardens, don't nest in corncribs, they don't do one thing but sing their hearts out for us. That's why it's a sin to kill a mockingbird."

To Kill a Mockingbird is perhaps our foremost example of the private reading experience writ larger by its communal--and now multigenerational--replication. Fans and the indifferent alike can remember when and where they were when they read the book, voluntarily or not, for the first time. Recollection of that memory of reading, perhaps even more than the book itself, is the reason To Kill a Mockingbird has become an enduring metaphor for justice, goodness, and the bittersweetness of growing up.

From the May/June 2011 issue of The Horn Book Magazine. See also "From the Guide: More Mockingbird."