IT IS easy to tell that Will Smith has embarked upon a serious movie project, because he has traded his movie-star grooming for an early-1980s shaggy moustache and an unruly crop of hair. The new look just screams "based-on-a-true-story," as well as a possible Oscar bid. And indeed, this time out Smith lends his considerable charisma to the role of Chris Gardner, a real-life San Francisco entrepreneur whose idea to sell portable bone-density scanners to Bay Area hospitals turns sour when it becomes evident that his product is more of a medical luxury than a necessity.

His wife, Linda (Thandie Newton, stuck here in a shallow, shrewish role), loses patience and leaves her husband in charge of their son, Christopher (played by Smith's real-life son, Jaden Christopher Syre Smith). Christopher attends a day-care center so cheap that the children's activities consist of Love Boat reruns. (The movie's title comes from a misspelling on a mural outside the day-care center.)

Looking for new work, Chris manages to land a highly competitive, unpaid internship at Dean Witter, with only the vague promise of a job at the end. While he dutifully slogs through his days, his funds grow ever shorter, forcing father and son to new indignities, such as spending the night in BART stations. Eventually he discovers the good graces of the Rev. Cecil Williams (who appears as himself) and Glide Memorial Church, but he must be in line every day before closing.

Smith also narrates the tale, looking at it in the past tense, which softens the blow of this otherwise difficult material. Italian director Gabriele Muccino crafts the movie as a typical, though sometimes effective, melodrama. As with his film The Last Kiss (remade earlier this year with Zach Braff), Muccino is quite skilled at hitting all the appropriate emotional peaks and valleys, although his hard logic leaves a bit to be desired. In The Last Kiss, that doesn't matter much, but in The Pursuit of Happyness, he misses out on crucial details, such as how Gardner managed the daily charade of working in an office environment while essentially being homeless. How did he keep his shirt clean and ironed, for example?

Perhaps even more disturbing is the movie's attitude toward the class system. Here, the wealthy are mainly kind, generous folk, and the poor are angry and vindictive. Gardner's ambition is admirable, but the movie dimly believes that great wealth is the final answer to all his problems (a title card informs us that Gardner retired a millionaire). Indeed, Smith's previous film, Hitch, had more to say about the real world than this film does.

However, The Pursuit of Happyness gets great mileage from Smith's onscreen relationship with his son. This little charmer is kept blissfully ignorant of his father's hardships and has a roster of delightful kid jokes at his fingertips. Even the biggest Grinch in the audience will find it hard to resist this genuine warmth.

The Pursuit of Happyness (PG-13; 117 min.), directed by Gabriele Muccino, written by Steve Conrad, photographed by Phedon Papamichael and starring Will Smith and Jaden Christopher Syre Smith, opens Dec. 15.

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