Knowledge workers are breaking free of the concept of a job for life. But to build a successful career they must not only update their skills, but also learn to sell them in an increasingly demanding market- place.

Roger Trapp reports on `portfolio working'.

Today's graduate entering the world of work has long grown used to the idea that the job for life - if indeed it ever existed - has gone. In many cases, he or she probably will not want that kind of employment. However, attractive as a life working at several different jobs may sound, it is difficult to know how to prepare for it. Traditional education does not fill the gap.

This is because, says the author and consultant William Bridges, it is based on meeting the requirements of the job as defined by the Industrial Revolution. Whereas before then society had largely been characterised by professionals, artisans and labourers offering their work as and when it was required, the changes of the 18th and 19th centuries produced a need for more people to be gathered together in one place to be on permanent call to whoever had hired them on a semi-permanent basis.

Thanks to new technology, we are used to "knowledge workers" being able to break free from these constraints and, to varying degrees, set their own work rules. But Mr Bridges, whose new book Creating You & Co (Nicholas Brealey, pounds 12.99) is published tomorrow, maintains that "dejobbing" or "portfolio working" will extend far beyond IT and the professions.

In fact, he believes that the background of many of these people makes them temperamentally unsuited to a life without traditional security, whereas people who have grown used to "hustling" through working as cleaners, say, or in adaptable family businesses, may thrive.

The book, whose UK publication date coincides with the author's "Redefining Work" lecture at the Royal Society for the Encouragement of Arts, Manufactures & Commerce, is designed to complement his ground-breaking work, Jobshift. The RSA invited him to speak because the "Redefining Work" project is designed to provoke a debate about what happens as work patterns change. It is intending to produce a broad view of the impact these changes will have, for example in companies with fewer "career people", and in the housing market.

The 1993 book Jobshift - which introduced many readers to the idea of a world without jobs, though not without work - has arguably accelerated the pace of change, which makes it all the more vital to be able to cope with the new situation. Commenting in the new book's foreword that "it's time we found a new way to think and talk about work", Bridges says that we need to "abandon the vehicle that has got us this far and strike out on foot for a while".

Though he admits that this is "a frightening prospect", he knows from his own experience of making the transition from literature professor to consultant and author that certain things can help develop what he calls a "customised career". The new book contains a series of aids to develop the individual and present him- or herself in a new way.

"Data", the acronym for this process, stands for Desire, Abilities, Temperament and Assets, and the author sees them as replacing what he calls the "three Es" - Education, Experience and Endorsements - as qualifications for work. In other words, today's youth cannot rely on what they have done; they must demonstrate that they really want work, that they can make things happen, that they have a "warm", social side to their personality, and that they possess skills or experiences that may be relevant for a particular situation. Things that fall into this category include growing up in a Swedish family, if the company with which you hope to work is planning to expand into Scandinavia, having reordered a small business's records, if you are applying for work that involves reorganising a filing system, and so on.

In addition to all this, according to Bridges, you have to "mine" it - by assessing what you want to do, what you are good at and what attributes you can draw upon. Then, just like any other conventional entrepreneur, you have to have a "product" that distinguishes you in the market.

The author accepts that some of the old ways remain. For example, magazines still run articles about the best jobs for the new century, while governments track job figures as if they provide the best measure of a society's health. He acknowledges that the changes are so profound in their implications, not least in politics, that governments, business, professions, schools, colleges, trade unions and the rest must get together and reassess the situation.

He insists that his readers will have a head start. "For at least another generation, people are going to be the old job-hunting thing. Like people who, when the key won't go in the lock, just jab it in again and again, they cannot see that they are operating on the wrong assumptions. We're entering a new age, folks, and we're going to be working out the implications of that fact for as long as we're around."