Saying no to your children has become one of the most difficult aspects of child-rearing in the late 1990s. Having suffered from over-disciplined childhoods themselves, many parents feel very uneasy about reacting negatively to their children. Others feel guilty about having less time for their children - and therefore believe that the time they do share together shouldn't be marred by squabbles.

However, are parents shirking their responsibility by allowing their children to make decisions about their everyday welfare before they are ready to do so? Does the absence of the "no" word mean that such children will become little emperors, ruling the family home without either the maturity or wisdom to do so?

Saying No, by child psychotherapist Asha Phillips, is an enlightening new book which combines the sensitivity and insights of psychotherapy with the age-old wisdom about children's needs for limits and boundaries.

"It seems so obvious that we should say no at times, yet the common assumption is that we should say yes whenever possible. There is an unspoken rule that if you are kind, caring, polite or thoughtful, you do not say no," Phillips writes.

Following her training at the Tavistock Clinic in London, Phillips has worked in both child-guidance settings and in a hospital paediatric department. From her experience in both, she believes that the difficulty in saying no has been central to some people's problems with their children.

"Saying no does not have to be a denial or crushing of another; in fact it can demonstrate a belief in the strength and abilities of others," she writes. Drawing examples from her clinical and personal experience (she has two daughters of her own), Phillips clearly validates her argument.

Take, for example, baby Jim - whose mother seemed always to know what he wanted and often anticipated his every need. "At the time I thought she must surely be the ideal mother," writes Phillips. "When Jim was 11 months old and not yet walking, he loved to hold on to his mother and with her help `climb' up and down the stairs. She would hold his hands and he would launch himself up with no regard for his mother bending over to support him. He would demand this activity for long periods of time and she seemed unable to make a stand about when to stop."

However, over time, Phillips realised that Jim's tolerance for frustration was very low and that he really found it hard to manage difficulties. His mother indulging him did not build up either his physical or emotional strength.

And by believing he was doing it all by himself, he was also denied the experience of developing his own means or the understanding that he needed her help. "By saying no, Jim's mother would have given him an idea of what he could or could not do by himself, as well as of what she could manage easily and what this activity cost her. Her reluctance to stand up to him encouraged him to become a little despot," says Phillips.

Like many psychotherapists before her, Phillips believes that the early communication between parents and their children lays down the foundation stones for much of the emotional development that follows. Always providing the answers for babies and toddlers prevents them from finding out what it is like to be left with a dilemma.

Parents sometimes need to learn how to acknowledge and tolerate grumpiness rather than to always be at hand with a solution. Such a strategy, Phillips suggests may prevent the "I'm bored" syndrome of children of primary-school age. It also allows the child to learn how to linger, ponder or simply be thoughtful - instead of restlessly reaching out for action all the time.

THE RESIDUAL EFFECTS of the parents' own upbringing are a crucial factor in the saying no or not saying no equation. This factor comes into play in a strong and sometimes unbearably frustrating manner with toddlers. Small conflicts can easily become inflamed into major arguments between child and adult.

Phillips cites another example which illustrates this point. "Mr B is a gentle man who finds it hard to say no to his son, Jack. When he does, Jack reacts with such passion, Mr B feels his son sees him as wicked. He tries to reason with him, who only gets more inflamed and acts as if Mr B would hit him, which he has never done. Mr B then gets quite angry inside himself with Jack for the image of himself he sees reflected in Jack's eyes, that of a nasty, brutish father. "What starts off as setting a simple limit turns into a big argument and upset for both of them."

Such a scenario - when the child and adult's interpretation of the event differs hugely and the difference exacerbates the situation - is familiar to many of us with pre-school (and older) children. Being aware of the origins of your own reaction is the first step to preventing unnecessarily fraught encounters.

Battles of will with toddlers are also not a good idea, simply because they reduce the adult to the level of the child, putting undue pressure on their relationship. "Many a parent of this generation can burden the child with lectures and defensive explanations," says Phillips.

"What is of value is to hold on to your role as an adult: to feel for your child and the state he is in, as well as being able to think about what is best for the two of you. You need to retain your own self-respect and convey to him that your `no' has a reason."

Saying No by Asha Phillips was published yesterday (Faber and Faber, £8.99 in UK).