A California Supreme Court decision last month ruled that denying gay and lesbian couples the right to marry violated the state constitution. California follows Massachusetts, which in 2004 became the first U.S. state to legalize same sex marriages.
A lesbian couple, 87-year-old Del Martin and Phyllis Lyon, 83, who have been together for 55 years, were the first to marry in a ceremony in San Francisco presided over by Mayor Gavin Newsom.
The newly-designed marriage license applications have replaced the words Bride and Groom with Party A and Party B.
Meanwhile, opponents see the move as a threat to the definition of marriage as a union between a man and a woman. Gay marriages have so far been rejected by 45 states although New York recognizes the same sex marriages registered in other states.