Parents pressure both teachers and their children for higher grades. Students tend to shun math and science, bypass dress codes and spend their weekend nights in theaters and discotheques.

Life in Bulgarian high schools has taken on a distinctly western flavor lately -- and government authorities are determined to stamp it out. A new ordinance has established a 9 p.m. curfew for those 18 and under, banned them from theaters, discos and restaurants serving alcohol without being accompanied by a parent, and made uniforms obligatory.

Parents and children who violate "the norms of socialist behavior" will be subject to "severe sanctions," the Communist Party newspaper Rabotnichesko Delo said recently, and Bulgarian officials make clear that "socialist behavior" in this Balkan nation of 9 million means strictly obeying the rules.

"A school without discipline is like a water mill without water," said Peter Balkanski, the deputy director of the government Research Center on Youth. "The young people who break school regulations today will be the bearers of antisocialist activity tomorrow. They will commit suicide. They will get involved in all sorts of amoral activities, such as rape."

In fact, youthful deviance has yet to cause such problems in Bulgaria, at least by western standards. But the crackdown on students reflects growing official concern about a slackening of order in what has been one of Eastern Europe's most regimented and self-isolated Communist-ruled countries.

"The Bulgarians have had a lot of trouble recently, especially in the economy," a western diplomat here said. "So there is a concern with discipline that is reflected in all aspects."

The problems, as Bulgarian officials perceive them, only begin at school. The state-controlled press has complained recently of sloppy management and planning, declining worker productivity and petty bureaucratic corruption. In a country with a substantial ethnic Turkish minority, reports of a rapidly declining birth rate among the native Bulgarians have prompted alarm.

In a rare public statement, the Soviet ambassador to Bulgaria recently criticized Bulgarian workers for their lack of productivity and said the working class was not "proletarianized" enough. Some western observers interpreted the statement as a call on Bulgarian authorities to emulate the Soviet Union's own recent discipline campaign.

Even before the Soviet warning, authorities were moving to tighten social controls. A new family code was issued last July that considerably toughened grounds for divorce and contained new provisions for child care. Other new laws restricted the spread of video equipment and cassettes -- a growing source of western influence -- and banned the sale of alcohol before noon.

Most of the new measures, however, have concentrated on youth. Early this year, authorities moved to limit the amount of western music played on radio stations. In September, a new law required graduates to find a job within four months of completing their degrees. Then came the crackdown on high school students, communicated to parents in special assemblies at schools last month.

According to Balkanski, official concern about Bulgarian youth has risen as plans are made to propel the country's economy into a new stage of high technology. Despite the official stress on technological development and strong incentives to attract talent, interest in science and engineering studies is dropping rather than rising among the young, he said.

The declining interest is due in part to poor school curriculums and restricted opportunities for graduating technocrats, authorities concede. In response, courses recently have been updated and reorganized, they say.

Balkanski, however, said that students also had developed "irresponsible attitudes about schooling," and these were manifested in "smoking and drinking spirits." "Young people misused the right to go to movies or theater or discos unaccompanied," he added, "and it had particularly bad effects on the sexual contacts of young people."

Not only western influences are to blame, Bulgarian officials say. Parents have been singled out for encouraging their children to study arts and humanities rather than technical subjects and for pressuring teachers in schools. "Parents forgot their duties," Balkanski said. "The root of the problem is an incorrect attitude toward labor in the sphere of production . . . basically created by parents."

"The society," Balkanski added, "should take more and more care of the training of attitudes of young people. The Bulgarian family is incapable of finding employment for its children."

Such intervention does not come without controversy. Diplomats say the measures have been unpopular, and Todor Angelov, the secretary general of the Ministry of Education, conceded that at least one aspect of the new regimen -- identity cards for students -- "is still controversial" and might be withdrawn.

In a meeting with western reporters, Angelov denied some restrictions reported by diplomats here, such as a code requiring girls with long hair to wear it in ponytails. "Some headmasters try to be overzealous," he explained.

Angelov agreed, however, that tighter controls were needed. "This decree is at the disposal of teachers and only reminds of certain requirements of the rules of our schools," Angelov said.