You know you're supposed to have a will. Whether you have one is another matter.

But you may not know that a will is just one of a handful of documents that most individuals should have - and too many don't have.Like a will, the other essential papers deal with subjects we would all like to ignore: death, disease, family disaster. But all are important to provide for your family and yourself.

Give yourself a gold star if you have all five of the following: a will, updated in the past five years; a power of attorney; a health-care power of attorney; a living will; a financial inventory.

If you came up short, you've got lots of company. "About 80 percent of our new clients have something" on the list, says Jeff J. Saccacio, a Los Angeles financial planning partner with accountants Coopers & Lybrand.

The percentage who have got it all? "Only about 20 percent at best."

But there's really no excuse not to have these documents. Getting them really isn't that hard. And when you need them, they are invaluable.

Although many people think of a will as a tool to parcel out assets, "my main concern is always the human element," says attorney Stuart K. Taussig of the Chicago firm Shefsky & Froelich.

If you have young children, the most important provision is the selection of a guardian who would bring up the kids if both parents died. For business owners with adult children, the challenge is to allocate the business and other assets so that the parents' deaths don't trigger a bitter fight.

But even people of modest means need wills to make sure their money goes where they want. Die without a will and there's no money for your favorite charity or someone you are involved with in a long-term but nonmarital relationship. State law might divide your money equally among a surviving spouse and children, even though many people would rather it all go to the spouse.

Writing a will calls for experienced professional legal help. Even for people who manage their own portfolios and do their own taxes, it pays to call a lawyer.

For instance, certain goals are met by having your will direct money to others in trust, rather than outright. Trusts can reduce taxes on big estates. They can also gradually parcel out an inheritance to orphaned children who would otherwise receive - and possibly fritter away - a large sum at age 18.

"Would you want to have a college kid with a million dollars in his or her name?" asks Taussig. "Most parents do not."

Leave the original of your will with the attorney - not in a safe-deposit box that might be temporarily sealed at your death.

Who would tend to your banking and other financial affairs if a serious illness or other crisis left you unable? Your family could go to court to get a guardian appointed.

Or, in advance, you could authorize a spouse or other trusted individual to make financial decisions for you.

The "power of attorney" that names such an agent is a simple and handy document - but also a potent one. "A power of attorney is a license to steal," cautions Washington attorney John Freeman Blake. "You have to be granting this power of attorney to someone you know won't rob you."

You can revoke a power of attorney by tearing it up. Some people tell the selected agent about the power of attorney but then leave the document with the lawyer who prepares it.

Some mutual-fund companies and other financial institutions may balk at the particular power your attorney prepares. To minimize problems, you want specific language about powers of investment, says attorney David Scott Sloan of the Boston firm Sher-burne, Powers & Needham. If you have big accounts at a couple of firms, consider showing the firms your power of attorney or also executing the particular forms those firms prefer.

A health-care power of attorney authorizes someone to make medical decisions for you if you are temporarily or permanently unable. It's usually coupled - sometimes in a single document - with a living will in which you indicate the type of care you would want if you were terminally ill or permanently unconscious.

Contrary to what many people believe, a living will isn't just for people who want to avoid being sustained indefinitely on mechanical life support. It is to spell out your personal wishes, "which may be that you want extraordinary medical procedures as long as you are alive," says Glenn Pape, a vice president with planners Ayco Corp., an American Express Co. unit in Albany, N.Y.

These documents can minimize family squabbles and ease the terrible burden on loved ones at life's said Taussig.

Many lawyers prepare a health-care power of attorney and a living will when they do a will. But if you don't need to see a lawyer now, you can get the proper forms for your state at no charge by calling Choice in Dying Inc., a national not-for-profit group (800-989-9455).

Give photocopies of your documents to your agent and doctor and make sure your agent knows where the originals are stored. Don't put the originals in a safe-deposit box to which your agent doesn't have access.

The last step is a personal financial inventory that lists, in plain English, the professional advisers, insurance policies and investment accounts that your survivors might otherwise have to scramble to find in the event of your death or other crisis. Use a work sheet supplied by an accountant or other adviser, or simply do it yourself.

Among the items to record: names and phone numbers of your attorney, your accountant and other chief advisers; location of important documents such as wills, powers, property deeds; a listing, with account numbers and document location, for all insurance policies, bank accounts, investment accounts, credit-card accounts and loans; and the location of safe-deposit boxes and of the box keys.

For husband and wife, the inventory can pull together basic information on the separate financial matters that each one routinely handles.

Be sure both spouses, and possibly other loved ones or advisers, know where the inventory is stored. "If something happens to you," explains Mr. Saccacio of Coopers & Lybrand, "there doesn't have to be a tremendous scramble to find this."