The Dalai Lama is found rather than chosen. He is believed to have the power to choose the body into which he is reincarnated, meaning that the current Dalai Lama is a reincarnation of the last.
The search for the reborn Dalai Lama is the responsibility of the High Lamas of the Gelgupa tradition and the Tibetan government.
This process can take several years: it took four years to find the 14th (current) Dalai Lama, Tensin Gyatso. The search is generally limited to Tibet, although the current Dalai Lama has said that there is a chance that he will not be reborn, and that if he is, it will not be in a country under Chinese rule.
To start the search, High Lamas may have a vision or dream. If the previous Dalai Lama was cremated, they watch the direction of the smoke to indicate the direction of rebirth.
They often meditate at Lhamo La-Tso, central Tibet's holy lake, and wait for a vision or indication of the direction in which to search. This relates to a belief that the female guardian spirit of the lake promised the first Dalai Lama that she would protect the reincarnation lineage.
When these visions have been followed up and a boy found, there are a series of tests to ensure that he is the rebirth. There is a secret set of criteria against which the child is assessed. In addition to this, the main test consists of presenting the boy with a number of items to see if he can select those which belonged to the previous Dalai Lama.
If only one boy has been found, the High Lamas confirm their findings with eminent religious and secular figures before reporting to the Central Government.
If more than one boy is found, a public lot is drawn by officials and monks.
The boy and his family are taken to Lhasa, where the boy can study the Buddhist sutra to relearn knowledge accumulated in previous lives in preparation for spiritual leadership.