Born in New York City, Mandel was raised in a household of six headed by his taxi driver father. When he was older and on his own, Mandel moved to Los Angeles to begin a screenwriting career, where he sold jokes to various comedians like Joan Rivers. In 1981, Mandel met future writing partner Lowell Ganz at the famed Comedy Store, which soon blossomed into a vibrant career would end up becoming arguably the most successful comedy tandem in cinema history. The pair made the first of many collaborations with producer Brian Grazer and director Ron Howard on their feature debut, "Night Shift" (1982), a comedy about a soft-spoken morgue attendant (Henry Winkler) whose quiet shifts at night get turned upside down when his overeager assistant (Michael Keaton) convinces him to use the morgue as a brothel. The film became a cult hit and made a star out of the outlandish Keaton. The pair reunited with Grazer and Howard on "Splash" (1984), a romantic comedy about a man unlucky in love (Tom Hanks) who falls in love with a strange, beautiful woman (Darryl Hannah) who happens to be a mermaid that saved him from drowning when he was eight years old. Both a critical hit and huge box office success, "Splash" also earned Mandel and Ganz an Academy Award nomination for Best Original Screenplay.Mandel and Ganz took a step back with the rather unfunny John Landis comedy, "Spies Like Us" (1985), which followed two loser CIA agents (Dan Aykroyd and Chevy Chase) who are suddenly thrust into the Cold War after cheating on their service exams. Moving on, they wrote "Gung Ho" (1986) for Ron Howard and Brian Grazer, a culture-clash comedy about an American automobile factory taken over by the Japanese at the behest of the plant's wheeler-dealer foreman (Michael Keaton). The film spawned a short-lived series, "Gung Ho" (ABC, 1986-87), which involved virtually none of the original cast from the feature. Following the commercial failure of Cyndi Lauper's feature debut "Vibes" (1988), Mandel and Ganz had one of their biggest hits of the time, "Parenthood" (1989), an ensemble comedy chronicling the pratfalls of being a parent as seen from differing points of view, including a father and mother (Steve Martin and Mary Steenburgen) dealing with their high-strung son (Jasen Fisher), and a single mom (Dianne Wiest) trying to raise her moody son (Leaf (Joaquin) Phoenix) and independent-minded daughter (Martha Plimpton) on her own. "Parenthood" was another huge score for the writing team, earning over $100 million in domestic box office gross while receiving near unanimous praise from critics.Ganz and Mandel followed up with another big hit, "City Slickers" (1991), a genuinely funny and sincere comedy about a down-and-out middle-aged urbanite (Billy Crystal) who is convinced by his two best pals (Bruno Kirby and Daniel Stearn) to go on a cattle drive in rural Montana, where they meet a rough-and-tumble cowboy (Jack Palance) who ends up teaching them a thing or two about life. Once again, the duo scored a huge hit with critics and audiences, while also brushing against Oscar glory when Palance won a statute for Best Supporting Actor. For their next project, Mandel and Ganz collaborated with Crystal again on the actor's directorial debut, "Mr. Saturday Night" (1992), an unfortunately bland comedy-drama about a comedian (Crystal) whose self-destructive behavior keeps him from rising above his five-decade long mediocrity. The duo rebounded with "A League of Their Own" (1992), a heartwarming comedy about the formation of an all-female professional baseball league to fill in the gap left by men fighting in World War II. Starring Tom Hanks as a recovering alcoholic struggling to manage his misfit team which includes Geena Davis, Rosie O'Donnell and Madonna, the writing team scored a big hit artistically and creatively. After soft-peddling a potentially dark and satirical comedy, "Greedy" (1994), starring Michael J. Fox, Mandel and Ganz wrote the inevitable sequel, "City Slickers II: The Legend of Curly's Gold" (1994), which failed to capture the warmth, laughs and box office dollars of its predecessor.In another collaboration with Crystal, they penned the script to "Forget Paris" (1995), the actor's second venture as director, which told the tale of an NBA referee (Crystal) who travels to Paris to bury his deceased father and meets an airline attendant (Debra Winger) whom he marries mere days later. After two relative box office failures with "Multiplicity" (1996) starring Michael Keaton and "Father's Day" (1997) with Robin Williams, the duo became two of several writers who shared credit on the screenplay for "Stuart Little" (1999), the story of a little mouse with a big heart who searches for a sense of belonging and a place to call home. The hybrid animation and live-action feature raked in a ton of box office cash and spawned the sequel, "Stuart Little 2" (2002), for which Mandel and Ganz were uncredited for their work. Meanwhile, the writing team ventured into cultural satire with Ron Howard's "EDtv" (1999), which depicted an Everyman (Matthew McConaughey) whose world is turned upside down when his life is recorded on camera 24 hours a day for a foundering cable station. With obvious comparisons to "The Truman Show" (1996), "EDtv" failed to dig deeper into that familiar territory.After penning the sentimental coming-of-age drama, "Where the Heart Is" (2000), Mandel and Ganz spent the next few years performing uncredited rewrites on a number of high-profile projects. Emerging five years later, they returned to the fore with two sharp hits, "Robots" (2005), an animated adventure about an idealistic robot (Ewan McGregor) who travels to the Big City with the hope of making his clanky, mechanical world a better place, and "Fever Pitch" (2005), a romantic comedy about a rabid Boston Red Sox fan (Jimmy Fallon) who finds his new relationship with a corporate executive (Drew Barrymore) suddenly deteriorating once baseball season starts. Though nowhere along the lines of "Parenthood" and "City Slickers," both movies announced a return to form that had been lacking in the latter half of the previous decade. But any good will they earned soon evaporated when they once again found themselves as members of a larger screenwriting committee on "The Tooth Fairy" (2010), a ridiculous, albeit successful comedy in which Dwayne "The Rock" Johnson played a tough-as-nails hockey player sentenced to hard labor as a real tooth fairy for discouraging a youngster's dreams.