Undated (AP) _ Public school officials in many cities praise the year-round schedule adopted by Los Angeles, but parents' opposition and lack of incentive to change have kept all but a few systems on the traditional nine-month plan.

''Theoretically it makes all the sense in the world,'' said Wayne Teague, Alabama Superintendent of Education. '''I've supported it for years, but the logistics would work havoc with a family.''

The Los Angeles Board of Education voted Monday to put the nation's second- largest district on a year-round schedule beginning in July 1989 in an effort to ease overcrowding without having to build new schools.

Under the plan, students in the Los Angeles Unified School District would likely attend classes for two months, then have 20 days off before returning for another two-month segment.

''I don't see that they have any choice,'' California state schools Superintendent Bill Honig said. ''Otherwise they will have classes with 40 to 45 students and the quality of education will suffer.''

Although Honig said a year-round schedule can cut costs 15 to 20 percent, the debate in Los Angeles may not be over yet. Board member Warren Furutani, who supported the year-round plan that passed by a 4-3 vote, said Thursday that he now favors reconsidering the idea.

Other large urban districts have considered year-round schedules, but have rejected them for various reasons.

''It's nowhere right now,'' said Gloria Lesser, a spokeswoman for the Board of Education in New York City, the nation's largest district with 940,000 students.

''I think L.A. is probably in a very unique situation,'' said Herman Mattleman, president of the Philadelphia Board of Education. ''They have overcrowding. They have an awful lot of kids coming in all the time.''

His own district, like many other big city school systems, has a stable student population, Mattleman added.

Ninety-eight percent of the students in the 67 school districts that have year-round schedules nationwide are in Western states, said Charles E. Ballinger, executive secretary of the National Association for Year-Round Education, based in San Diego.

''I think that reflects largely the population shift west of the Mississippi,'' he said. ''Also, we're more open to trying new things. And certainly lifestyles are different in the West. People think about winter vacations more. The idea of summer vacations only is foreign to us.''

In Las Vegas, Nev., 15 of the Clark County School District's 84 elementary schools are on a year-round basis, district spokesman Ray Willis said.

''The reaction ranges from very strong support to very strong disapproval,'' Willis said. ''The majority of parents, given the choice, would probably opt for the nine-month schools.''

In Utah, 18 schools are on year-round schedules and the State Office of Education is expanding the program to cope with a growing school-age population, said Eileen Rencher, Utah Office of Education director of public affairs.

Rhode Island's Legislature last year created a commission to study the idea of lengthening the school day, week or year. But Ken Miller, assistant state commissioner of education, said the Los Angeles plan is not being considered by any district in the state.

''There are some cost savings that can be attributed to those (year-round) plans,'' he said. ''It's also a disruption to the social pattern of the community. What they have to do is balance whether the cost savings are worth the disruption and the social setting of the community.''

Nancy Kochuk, a spokeswoman for the nation's largest teacher's union, the National Education Association, said the NEA did not have a position on year- round schooling. She said, however, that teachers should be compensated if the length of the school year is increased.

In the only Missouri school district on a year-round schedule, the Francis Howell School District in St. Charles County east of St. Louis, parents and students are pleased, said Richard Schuppan, the district's assistant superintendent of elementary education.

''They enjoy vacations at different times of the year,'' Schuppan said. ''This gives them a break during each season - fall, winter, spring and summer.''

The Valley View School District near Romeoville, Ill., discontinued year- round schedules in 1980 after a decade because enrollment dropped, said Emmie Dunn, adminstrative assistant of the district.

''It did exactly what we wanted it to do,'' she said. ''Our parents did not want to go on it, but once they did, they loved it.''