The nation's first official do-it-yourself will has been incorporated into California law, reaffirming the state's reputation as the country's legislative laboratory.

The simple four-page form will was drafted by the legislature last year to help solve a problem affecting many if not most Americans: their reluctance to go to a lawyer and make out a will. State bar officials estimate that 57 percent of adult Californians have no wills, including 32 percent of adults with minor children.

Lawyers in other parts of the country have resisted proposals for statutory wills, arguing that a simple form is no substitute for expert legal advice catering to each person's peculiar situation. Two recent attempts in New York to legislate a simple will form failed. San Francisco attorney Harold Boucher attributes this to lawyers' fears "that they were going to lose business."

Boucher, 77, and several other California attorneys argue that the form should bring in more business by stimulating general interest in wills.

The new statutory form, which took effect Jan. 1, is scheduled to be on sale soon for $1 each at the state bar headquarters in San Francisco and at some book stores. Esther Mamet, manager of administrative and research services for the California State Bar, said her office has already received 7,000 requests.

"People are streaming in here, little old ladies and men. We feel terrible because we haven't finished printing them yet," she said.

Dee Erickson, general manager of Wolcott's Legal Forms and Stationery, said, however, that his firm has already sold wholesale and retail 15,000 copies of its own version of the form, at a retail price of 70 cents.

Jacoby and Meyers, a cut-rate chain of California legal clinics, charges $95 for a simple will, a secretary in the firm's West Los Angeles office said. Complicated wills may often cost as much as $500.

Inexpensive forms for do-it-yourself wills have been available for years, but lawyers here say the California form is the first to be codified in law, giving those who use it the assurance their will is legally valid if they have filled it out properly.

Attorneys here attributed California's success in passing the law to some of the same factors that have made it a leader in laws limiting real estate taxes and punishing drunken drivers--extremely well-financed and organized citizen groups, a sophisticated and politically liberal state legislature and a self-confidence and willingness to experiment because of its relative economic strength, particularly in the legal community.

"California has been kind of a leader in probate and trust law," said Mark D. Elrod, an American Bar Association official who is vice president of the First National Bank of Topeka. But he said the idea had been rejected in Kansas "because we know of no one form that will fit every need."

Paul Karan, former head of a similar committee for the New York bar, said the legislature there concluded that "the cure was worse than the disease" and could cause trouble for individuals who used the form without consulting an attorney.

A notice at the top of the California form warns that legal help might be advisable. Officials say the form should not be used by those who want to protect children from two marriages or who want to keep children's inheritances in trust past age 21.