Walt Disney Concert Hall has program notes for The Dharma at Big Sur, which includes a short Q&A with John Adams:
When the Philharmonic asked me for a new work to celebrate the opening of Walt Disney Concert Hall, I knew I wanted to write something that reflected our collective experience of being Californians. I especially wanted to reflect the experience of those who, like me, were not born here and for whom the arrival on this side of the continent had both a spiritual and a physical impact.
Adams also says that the piece is not improvised, uses just intonation, and was inspired by Jack Kerouac's book Big Sur. 11/29/03