When you're just starting out, you're worried more about preparing for your future life than for your death. It's little surprise, then, that many of the twentysomethings who died in the Sept. 11 terrorist attacks didn't have wills, says T. Randolph Harris, an estate-planning attorney with McLaughlin & Stern in New York who handled the estates of a number of Sept. 11 victims.

But writing a will is something many young people should include as part of their financial planning. Here's why.

When to Get One

It is absolutely critical to have a will if you have a child. We'll talk about that below. But even if you haven't gotten to that stage in life, you may want or need a will to direct what happens to valued possessions -- such as a dog, a car, an apartment you own alone or a special comic collection -- in case of your early death.

A will typically wouldn't control who gets "joint property" (such as a house you bought with your spouse) or accounts for which you have designated a beneficiary, such as 401(k)s and individual retirement accounts (and possibly bank and brokerage accounts as well).

But when it comes to your other assets, if you die "intestate," or without a will, your state's laws will determine who gets what. The distribution laws vary by state, but generally your possessions pass first to your spouse and children, if you have any.

If you don't, then most often your assets go to your parents, if they're still alive. If they aren't, then the order of succession is usually first to siblings, then to other living relatives, and finally to the state, says John McCabe, legislative director with the National Conference of Commissioners on Uniform State Laws. Check your state's probate code for details.

"The principal time to think about having a will is if you would want your estate to go differently than the way the state's intestate laws would distribute it," says Mr. Harris, who is also an executive committee member of the American College of Trust and Estate Counsel, an association of trust and estate lawyers.

Unless you have a will, a significant other you're living with won't get anything, nor would a favorite charity. One of Mr. Harris's Sept. 11 cases was a young man who was about to be married. Because he had no will, his estate went entirely to his family, and nothing went to his fiancée.

If you have children, a will lets you determine who will take care of them and manage their money if, say, you and your spouse die together in a plane crash. In addition, you can use a will to set up a trust for your children, so they don't get the inheritance until they reach a certain age.

If one parent dies, a will can make sure everything goes to the surviving spouse, and not partially to young children. If you don't do this, your spouse may have to go through hoops like filing certain papers and checking in constantly with a court to manage your children's money.

Keeping It Simple

A simple will is generally just a document that specifies how your assets will be distributed. It's typically formulaic. The outline is along the lines of "upon my death, take the assets that are in my name alone and here is who you give them to and how you give it to them," says Christine Albright, a trusts and estates lawyer in Chicago and chairwoman-elect of the American Bar Association's Section of Real Property, Probate and Trust Law.

If you're young, single and don't have significant assets (in the realm of hundreds of thousands of dollars), you could consult do-it-yourself books or software programs from companies like Nolo that can guide you through simple will writing. Nolo offers a software program called Quicken WillMaker Plus, which costs about $50. Later this year, it plans to offer an online will that can simply be filled in ( www.nolo.com ).

A guide such as the American Bar Association Guide to Wills and Estates, available in bookstores for under $20, also can help.

Range of Costs

If you hire a lawyer, charges for wills generally start at around $250 and run up to more than $1,000 for a young married couple who just had their first child, Mr. Harris says.

Ask people you know for referrals or try the lawyer locator at the American Bar Association's Web site ( abanet.org ) or the site of the American College of Trust and Estate Counsel ( www.actec.org ).

Getting help from an attorney could help ensure you don't miss important nuances of will writing or use words or terms that have legal meanings different from what you intend, lawyers say. If you have lots of assets, talk to an attorney about options to minimize probate fees and estate taxes, such as by using various trusts.

Regardless of how you make the will, to be official it must say it's your will, it must be dated and signed by you, and it generally also must be signed by two people who witnessed your signature. The witnesses should not be people who will inherit your assets. You don't need your will notarized, but doing so can help save your witnesses later hassles of having to testify that the document is your will.

Finally, you'll also want to include a living will and other health components in your final documents. In a living will, you can say how you would want to be treated if you can't make decisions about life-sustaining medical treatment. (For example, would you want a feeding tube?) That's a document you can't have early enough, says Peter Bielagus, a financial adviser for young adults.

Generally, you'll also need documents naming someone to make health decisions for you and someone to handle your financial issues for you if you are not capable.

Preserving the Documents

Once you have all your end-of-life documents prepared, you'll need to put them somewhere for safekeeping.

If you have a lawyer, the original documents are usually kept at his or her office. Keep a copy in a secure and easily accessible place where someone looking could find it -- say, with your other important papers in a file cabinet or in a fireproof box.

Ms. Albright advises against keeping your will in a safe-deposit box since getting into the box could be a hassle for the people you leave behind and could require a court order. "A safe-deposit box is not usually a good idea."