The Nostarë Olinwa

Amongst the elves of Kyrn, a special birthday celebration occurs during the year of a young elf's 20th birthday on the summer solstice.
During the first 20 years of an elf's life, they are considered children, and are treated as children. They are taught all the things that children need to learn, but in the year that they will have their 20th birthday, they become adults, and are expected to start taking on the responsibilities of adulthood. Up until their 20th birthday, families have small private celebrations on the child's birthday.
In the year of their 20th birthday, all the elves in the community, join together to celebrate the Nostarë Olinwa when children transition to adulthood.

Execution

The Nostarë Olinwa starts one week (10 days) before the summer solstice with the gathering of the community. Those elves that live solitary lives away from the village also take this time to come into the nearest community to participate in this important celebration. The first several days of the celebration involve the elders talking to the community, but specifically to those coming of age, about the needs of the community, and what roles the community needs filled by the soon-to-be adult members.
During the next several days, those coming of age speak with the elders and decide what roles they will take on when they become adults. Most of them choose, to follow in their parents footsteps, but there are usually a number of openings with some of the more esoteric roles, such as in the priesthood, or apprenticing to a wizard, or a druid, or committing to the defense of the village as a soldier, or a ranger. Many of these positions have limited openings, so there is a series of interviews and challenges to find the best fit for each of those coming of age.
On the summer solstice, feasting and partying start the day, and then at noon, the Announcements begin, with each new adult being called before the assembled community, and then the elder, or parent, that has decided to mentor the new adult steps forward and proclaims that the elf will be his trainee. Each announcement is meet with cheers and celebrations as the new adult is accepted into their new role as a contributing member of the community.
Occasionally, a new adult doesn't get the mentorship that they were hoping for, but that they put aside their own feelings to do what is best for the community, knowing that they have a long life ahead of them, and the opportunity to change paths will always be before them. It is expected that the new adult will do their best at the role they have been assigned for at least a year before they look to change their path.
After the Announcements are over, the community continues to feast and dance and sing until the following dawn, when the party breaks up, and the new adults say goodbye to their childish selves, and if needed gather their things and go to their mentors.

Components and tools

During the Announcements, a large ceremonial bowl of wine is used. It is first handed to the mentor, who after announcing that he has accepted the new adult under their tutelage takes a drink, and then hands it to new adult who drinks from it as well, symbolizing the agreement to transfer knowledge and skills from the mentor to the apprentice.

Translation from Elvish:
Coming of Age Day
The birthday of being fully grown