In the not-too-distant past, a man walking into a Reform synagogue wearing a yarmulke, the skullcap worn by many Jews, would be asked to remove it.

Reform Judaism was founded last century as a leftward movement, emphasizing social justice and rejecting many of the traditional rituals and practices regarding diet and dress as at odds with modern society.

But an increasing number of North America's 1.5 million Reform Jews are embracing observances cast off by their forebears. They are wearing yarmulkes, donning the prayer shawl called a tallit, keeping kosher kitchens, and learning Hebrew, all practices that would have been taboo a generation ago.

The move has been unsettling for some longtime Reform Jews, many of whom joined the movement to escape what they perceived was the rigidity of the Orthodox and even the Conservative. They fear ritual observance could replace Reform's commitment to social justice and tikkun olam -- repairing the world.

This week, the nation's Reform rabbis will gather in Pittsburgh -- where rabbis issued their first platform defining the movement in 1885 -- for a four-day convention. They will vote on a set of principles, for only the fourth time in the movement's history in this country, that will encourage congregation members to seriously study ancient Jewish tradition and embracewhat they deem appropriate.

Many raised in the Reform movement never thought they'd see the day.

"Definitely, Reform Judaism has changed since I was a youngster," said Joyce S. Ottenheimer, a member of the Baltimore Hebrew Congregation in Upper Park Heights. "I'm seeing people I know who were raised in Reform congregations doing much more traditional things and adopting much of the ritual we never did before. There are still many of us who practice the same kind of Reform Judaism we grew up with."

To gauge the change, look at what some people are wearing.

"Gradually, there are more and more yarmulkes," she said. "You can tell the old congregation from the younger people because the older people don't wear them."

Reform Jews who like the move toward ritual also enjoy the freedom to choose those practices that suit them.

"I do enjoy the rituals and the traditionalism of Judaism, and that's where I'm comfortable in my observances," said Diane Israel, a member of Temple Oheb Shalom in Upper Park Heights. "I'm very comfortable with my husband if he chooses to wear a kipa [Hebrew for yarmulke]. My son wears a kipa every day. I'm comfortable with men wearing a tallit. I don't know Hebrew, so I'm more comfortable with a service that's in English -- so I can understand and pray in my own way."

The move to embrace tradition came to a head last year when Rabbi Richard N. Levy of Los Angeles, the outgoing president of the Central Conference of American Rabbis, proposed Ten Principles for Reform Judaism. That early draft advocated following a form of kashrut, the kosher dietary laws, and urged the use of Hebrew in the liturgy. It stressed the importance of observing the Sabbath; and it praised the use of the mikvah, the ritual bath to purify a woman after menstruation.

Even more startling for many was Levy's picture on the cover of last winter's edition of Reform Judaism magazine, in which he wore a yarmulke and kissed the fringe of his tallit.

"The picture of Rabbi Levy on the cover was so traditional," Ottenheimer said. "People, their eyes flew open."

The negative reaction to Levy's principles was so virulent in some quarters it was dubbed the "Cheeseburger Rebellion," a reference to the mixing of meat and cheese, forbidden under kosher law. Rabbi Robert M. Seltzer, in the same magazine issue, said the observances recommended by Levy "stand in startling opposition to the standards of Classical Reform Judaism, which has championed the image of modern Jews as dignified, respectable and mainstream."

Reform Jews must guard against turning their movement "into Conservative Judaism Lite," he wrote.

Levy said that people who read the early drafts of the principles thought that they were mandating religious practices. But his intention, he said, was to initiate discussion of Jewish tradition in synagogues. From that, people could decide what observances they wish to follow, and even adapt traditional observances to modern circumstances.

Take keeping kosher, for example. Levy offers the possibility that Torah principles might govern one's diet, although they might not be the same principles followed by Conservative and Orthodox Jews.

"The Torah is very clear that one should not benefit from the oppression of workers. The Talmud stresses concern for the pain of living creatures," Levy said. "To put into dietary practices concern for how animals are raised, conditions under which farm workers labor, if one can assist their cause by eating or not eating certain foods, that should be part of our practice as well."

After the December uproar, the Central Conference of American Rabbis board formed a committee, led by Levy, to rewrite the principles. After several drafts the result is a dramatic softening of the language.

"I'm frankly a little disappointed," said Rabbi Rex Perlmeter of Baltimore Hebrew Congregation. Levy's earlier drafts "challenged people in somewhat more specific language to evaluate their categories of observance, making it very clear that whether to observe is not a matter of choice," he said. "The choice is in the 'how,' not the 'if.' And I liked that challenge."

Although there is widespread discomfort in Reform Judaism with the notion of spiritual mandates, many rabbis welcome the grappling with tradition that Levy sparked.

"The move to encourage people to think more seriously about observance is very good. Whether it needs to be in traditional forms or not is where I see the value and importance of individual choice," Perlmeter said. "I really couldn't care less whether any individual Jew wears a kipa or a tallit. I want them to at least be comfortable in their presence and comfortable with why somebody might wear them."

Others, including Rabbi Donald Berlin of Temple Oheb Shalom and Rabbi Gustav Buchdahl of Temple Emanuel Synagogue in Reisterstown, warned that any move toward ritual must not be made at the expense of Reform's historical emphasis on ethics, rationality and individual autonomy.

"What is missing from my point of view is the statement about the criterion by which Reform Jews should come to conclusions about their faith and their life," Buchdahl said. "Namely, that it be rational, true and ethical."

There is a fear, Berlin said, "and I share that fear, that we get so involved with ritual that we will not use our reason, and we will not use our judgment, and we will lose that sense of ethical commitment, unless it's highlighted."

Also, there is the danger of alienating those who don't feel moved by Jewish observance. "We don't want people to feel disenfranchised because they're not ritually observant," Berlin said. "What we're looking for is, we want people to consider the option of ritual, not the mandate of ritual."

Ritual or no ritual, the one characteristic of Reform Judaism present here is the debate.

"That's one thing about Reform, it doesn't have an 'ed' on the end of it," said Ottenheimer. "It's still a work in progress. If it were 'Reformed,' it would be set in stone."