"In Her Shoes" has enough homespun wisdom to make you hurl, but the tone and acting are so sharp, it never feels like a sit-down with Dr. Phil.

A wry comedy about two sisters whose lives were shaped by their messy upbringing, "In Her Shoes" is a rare movie about families that actually seems to have been made by people who came from them. The script (by Susannah Grant, based on Jennifer Weiner's book) has compassion for human failings and insight into how people who grow up together can home in on each other's weaknesses.

The idea is that Maggie (Cameron Diaz) and Rose (Toni Collette) were raised by a manic-depressive mom who died, whereupon their father told them their grandmother (Shirley MacLaine) was dead, too. Maggie, who loved their mother's wildness, responded by becoming a wild woman herself - drinking too much and studying too little. In one of the many developments that feels genuine, Rose's response was the opposite - she studied too much, partied too little and sprang for too many never-worn pairs of designer shoes. But, eventually, the sisters tire of their roles and decide to walk a mile in each other's Jimmy Choos.

Although the ads make "In Her Shoes" look like a Diaz movie, it splits its time evenly between the sisters, and Collette's performance is far superior to Diaz's. She finds rueful comedy in painful moments and melancholy in funny moments. In other words, she is real, which is why it means so much when Rose's boyfriend says probably the sweetest thing any character in any movie this year will say: "You look good. You look like you."

As good as Collette is, MacLaine may be even better, as a woman with 70-odd years of people smarts under her belt. MacLaine is not a sentimental actress; she knows we'll like her more if she doesn't appear to be begging for our sympathy. So, when Diaz asks why she's willing to do her a favor and MacLaine replies, "Because I'm your grandmother," MacLaine doesn't make the easy choice, which would be to say that line as if the rest of the sentence were "and I love you." Her choice makes more sense for her weary, compassionate character - she says "Because I'm your grandmother" as if the rest of the sentence is "and helping you is my job."There is an acknowledgment in "In Her Shoes" that being part of a family can be a job but that it's a worthwhile job because, to paraphrase Maggie, "without them, we don't make sense."