It's hard to think of "Madame Doubtfire" without getting visions of Robin Williams, and I suspect most people are unaware that the story of the father who poses as a female housekeeper in order to be close to his children was originally a Young Adult's novel by Anne Fine. With only about five years between the publication of the book and the release of the movie, there was very little opportunity for the book to stand on its own before being Americanized into Mrs. Doubtfire the movie (the book is set in Britain. Perhaps the American adaptation tries to compensate by making their Mrs Doubtfire claim she's British...and yet giving her a Scottish accent). The movie acts as a vehicle for Robin William's comedic talents, with the three children taking a backseat to the struggles and tribulations of their parents; what with Daniel attempting to find a new job that makes the most of his abilities, and Miranda dating a new love interest, all of which centers around Daniel's struggle to negotiate his role as Mrs Doubtfire with his real persona. Amidst all of this, the children themselves are barely noticed.
Fine's book on the other hand, is much more interested in the very-real damage that divorce proceedings has on young minds, and Lydia, Christopher and Natalie emerge as much stronger and more central characters. Beginning several months (perhaps years) after the divorce of Daniel and Miranda Hilliard, the children have formed their own ways of coping with the vicious fighting and bickering that goes on between their embittered parents, and it's quite heart-rending to read about. But after Miranda tells Daniel about her intention of hiring a housekeeper, Daniel tampers with the advertisement and then turns up on her doorstep - unrecognizable in drag. Calling himself Mrs Doubtfire, he soon makes himself indispensable to Miranda and the household, all the while covertly relishing the extra time he gets to spend with his children.
Although following the same basic plotline, Fine's book is considerably more British, as well as more focused on the children's welfare. As such, it is darker than the light-hearted family movie, with the children clearly suffering under the continuous vindictiveness of their parents, who seem to be more interested in making each other suffer than in taking care of their children on an emotional level. The children are considerably more intelligent that their movie counterparts, with Lydia in particular picking up immediately on her father's disguise, and all three of them helping their father keep his secret. Each one has different tactics of dealing with the new situation - most interestingly is young Natalie's way of dealing with her father's dual role by quite firmly refusing to acknowledge that Daniel and Mrs Doubtfire are one and the same.
There are other differences, including the fact that Daniel actually has a job as a nude model for the neighbourhood art class, as opposed to eventually landing a job as a television host, and the persona of Madame Doubtfire isn't given half the attention and affection that the movie gives her, eventually making her the host of a new children's television show. Here, the children themselves point out to their father that their time spent with Madame Doubtfire doesn't really count as quality time spent with their father since he's pretending to be someone else the entire time. Eventually it is the children themselves who exert control over their parents, informing them in no uncertain terms that they won't put up with any more nonsense from either Daniel or Miranda. In the best line of the book, Lydia declares: "Natty and Christopher and me, we are the only three things to come out of that marriage. We're all that's left. We're the whole *point* now...the only reason you have any real contact. So that sort of gives us an Extra Right. Don't you see? If we three aren't happy with the way things are, then what was the point of all those years? None! None at all! If you can't work things out to suit us, then it was all just a total waste and total failure." Now *there's* a good message for any child to dish out to their bickering parents, and I can't help but notice that the movie never even comes close to giving the three children this sort of agency and power.
It seems to me that the movie is catered more toward adults who are trying to deal with the pain of divorce, with hints on how to stay on good terms with the ex - the book is directed at children and the suffering they go through when their parents separate, and is sympathetic toward their plight. Although the book ends on a much more ambiguous note than the reasonably-happy ending of the film, Anne Fine's book is much more concerned with the wellbeing of children, and with giving them the message that they can survive the pain of divorce. I would go so far as to say that the book, with its messy, dark, unhappy look at broken families, is a much more truthful, sincere and ultimately helpful look at divorce than the movie version.