One of my favourite movies is “Failure to Launch”. Not because it's great cinema, I just like the premise.It's about a 35-year-old, played by Matthew McConaughey, who lives at home and has no intentions of leaving. So his parents hire a woman who specialises in getting grown men to leave the nest. There's much more to the story, of course, but the takeaway message for me is that parents need to help their adult children launch into adulthood. Unfortunately, there are many parents who fail at this task.An online poll commissioned in May by the National Endowment for Financial Education and Forbes.com found that nearly 60 percent of parents are giving, or have in the past granted, financial support to their adult children who are no longer in college. Half of the parents in the poll said they were providing housing for their adult children, and 48 percent said they were doling out money for living expenses.Because of today's weak economy and high unemployment, adults young and old have returned to their parents' homes out of financial necessity. But then too many stay long after they should have returned to the real world of paying their own bills.Then there are adult children who don't live at home but still feel entitled to their parents' money. The result is that some parents are tapping their savings cushion, taking on debt, delaying their retirement or not saving for their retirement because they can't cut the financial ties to their grown children.So, parents with adult children who haven't launched, what can you do?Well, I've got a book that will help you facilitate a long-overdue launch. For the Color of Money Book Club this month, I'm recommending “How to Raise Your Adult Children: Real-Life Advice for When Your Kids Don't Want to Grow Up” ($16, Plume). The book is written by Susan Ende, an experienced psychotherapist, and Emmy award-winning comedy writer Gail Parent.The authors package their advice in a question-and-answer format with each giving a separate opinion, which often differs. Parent provides the humour and Ende the practicality, as a therapist would.“Our primary focus when answering the questions in this book was to point parents in the direction of making decisions to foster their child's independence,” the authors write.Although Parent and Ende cover such topics as dating, marriage, in-laws, and living arrangements, much of the advice centres on money. Here are some of the financial-related questions they tackle:Should a father always pay for dinner when out with his employed daughter and her husband? “It's only really harmful when the kids expect more than a dinner out,” Parent writes. Ende doesn't agree. “Parents who routinely pick up the tab may feel good about it, but paying all the time does nothing for the adult child's self-esteem, nor for his sense of finally being equal,” she says.Should a father pay for a third trip through rehab for his addict son? Parent said no. Ende said pay maybe once, but not three times.A son, who is a successful dentist with a stay-at-home wife and two kids, asked his parents to financially support him and his family for a year so he could pursue his dream of becoming a writer. Both authors agreed the parents shouldn't put up any money. Say no to his “childish, unrealistic scheme,” Ende wrote.A daughter married a no-account who skipped out and won't pay child support. Her parents want to know if they should continue providing all the support for their daughter and granddaughter. Parent said let the two stay but push the daughter to get a job and pay for her and her daughter's expenses. Ende said the parents should help the daughter make a plan to eventually move out on her own.There's as much to learn from the questions as from the answers. I continued to be amazed at the reluctance of many parents to be candid about their reservations in supporting their grown children. I've found the word “no” to be one of the most powerful tools available in my parenting arsenal. I'm all for helping but not enabling. That's an overly expensive form of parenting.I'll be hosting a live online discussion about “How to Raise Your Adult Children “ at noon Eastern on September 22 at washingtonpost.com/conversations. Both Ende and Parent will be joining me to answer your questions. Every month, I randomly select readers to receive a copy of the featured book, donated by the publisher. For a chance to win a copy of “How to Raise Your Adult Children”, send an email to colorofmoney[AT]washpost.com with your name and address.Readers can write to Michelle Singletary c/o The Washington Post, 1150 15th St., N.W., Washington, D.C. 20071. Her email address is singletarym@washpost.com. Comments and questions are welcome, but due to the volume of mail, personal responses may not be possible. Please also note comments or questions may be used in a future column, with the writer's name, unless a specific request to do otherwise is indicated.(c) 2011, Washington Post Writers Group