Caste'n Day

The Dwarvish coming-of-age ceremony is when a clan member picks his caste. While different rules and traditions are followed by each clan, the base exists regardless of a dwarf's location or birth. While smaller halls tend to have individual Caste'n days, large halls have a single one each year, with a truly massive celebration in Crestfall on the last day of the year in the Hall of Stone.
The ceremony gives dwarfs a certain amount of social mobility and allows castes that are shrinking to gain new members. This is only slight mobility and reaching too far can cause someone to become casteless as you can only pick once. This results in most picking the same caste they were born in unless pushed to join another.