The first major dissident trial under the new Soviet leadership - and potentially the most important in many years - seems about to begin. It involves a handful of young people virtually unknown in the West and strikingly different from most dissidents tried and confined over the past 15 years.
Known as ''young socialists,'' the detained youths come mostly from well-off Soviet families. They espouse something akin to ''Eurocommunism'' and have quietly advocated reform of the Soviet system from within. At least one of the young men, friends say, worked at a prestigious Communist Party institute for foreign policy, known as IMEMO.
If intermittent media alarm bells over the ideological errings of some Soviet youths are any indication, the issue of the young reformers is a sensitive one for the Kremlin.
Unlike more clear-cut Kremlin opponents like physicist Andrei Sakharov or expelled novelist Alexander Solzhenitsyn, the young socialists speak in the language of Marxist-Leninists. The new leadership seemed to erase any doubt of its line toward such dissidents in January when they called in the dissident Marxist historian Roy Medvedev for a warning to cease ''anti-Soviet'' activities.
The defendants number at least five - six, by some accounts. The discrepancy is due to the fact that the young socialists have generally avoided contact with Westerners and with other dissidents.
The youths were arrested last April - when current Soviet leader Yuri Andropov was still head of the KGB - amid reported police searches of dozens of Moscow apartments.
The trial process, according to latest reports from dissident sources, is set to begin Feb. 15 with something akin to a preliminary hearing. It remains unclear whether the youths will be tried simultaneously.
They are said to be charged, under two Soviet legal articles, with ''anti-Soviet'' activity and with having belonged to an illegal organization. This last accusation could apply to any political group except the Communist Party and various officially sanctioned organizations like the trade unions.
Not only some Soviet officials here but even some dissidents view Yuri Andropov as more likely than the late Mr. Brezhnev to seek a measure of eventual reform-from-within. But dissidents see the trial of the young socialists as a signal Mr. Andropov is also intent on squelching any freelance contributions to such a process.
The young socialists' ''organization'' is said by friends to have been a very loosely constructed group - consisting mainly in translation and swapping of leftist political literature from abroad. A good deal of such writing is available here, but usually in the original language.
''These boys had the language capability to translate it,'' says one of their friends. In addition, the group circulated a makeshift typewritten journal.
Its main crime, under the Soviet system, seems to be that it contradicts the official credo that the Kremlin runs a socialist system. The youths argued that it is nothing of the sort, but instead one that has spawned a new class of exploiters which should, ideally, be replaced by ''real socialism.''