Why don't synagogues of movements other than Reform conduct a Confirmation ritual during the Holiday of Shavuot? Although it is an innovation, it doesn't per se seem so halakhically problematic, especially because it is about confirming one's belief in the Jewish faith. Sounds like a bit like Kabbalat ha-Torah, if you ask me...
(This section was written by Monica Cellio.)
Description of Reform Confirmation (can't speak for Conservative): While there is some variation, the confirmation ceremony typically includes the following elements (based on personal observation and discussions on Reform mailing lists):
Confirmation is in a group, not individual like bar mitzvah. The confirmands are usually finishing 10th grade, though a minority hold by high-school graduation instead. So roughly age 16. Confirmands are required to have continued their religious education after bar/bat mitzvah.
Confirmation is usually done as part of an evening service, either erev Shavuot or the erev Shabbat preceeding.
Confirmands usually lead part (sometimes all) of the service.
The rabbi or other community leader usually addresses the confirmands as a group. There may or may not be brief individual blessings/misheberachs.
If confirmands speak, it is about their Jewish values and aspirations.
Confirmation does not involve or acknowledge a status change. It is more about public declaration of one's continuing commitment to Judaism (not specifically Reform Judaism, though obviously they're Reform Jews).
Wikipedia article on Confirmation: (mainly discusses the Christian Confirmation, yet there is still some substance related to the Jewish Confirmation)
Below, I have posted a series of essays disputing this contentious issue that has been facing those of us who are part of the Reform community:
Historically, the Reform Movement has viewed Confirmation as a significant educational milestone on the path of lifelong Jewish learning. In some communities, B'nei Mitzvah has taken on a greater role in the life cycle of a Reform Jew, superceding Confirmation. Should Confirmation continue as the vital rite of passage that it has historically held or should Confirmation be discarded as a relic in favor of B'nei Mitzvah?