Emma Johansson of Sweden couldn't match Cooke's explosive sprint and got the silver medal. Tatiana Guderzo
of Italy, who attacked with about 13km to go to forge the winning breakaway, hung on to win the bronze.
Cooke snuck into the winning, five-rider breakaway after following the attacking Guderzo in the decisive second and final
lap of a 23.8km circuit at the end of the 126.4km Women's Road Race to claim Great Britain's first Gold medal of the Beijing
2008 Olympic Games.
The remaining rivals, including pre-race favorite Marianne Vos (Netherlands), hesitated in organizing
a chase and the leading quintet disappeared down the rainy, final descent to battle for the medals.
Rainfall, wind and unseasonably cool weather made for challenging conditions for the race.
Some 66 starters lined up on dry roads under cloudy skies at Yongdingmen in the south of Beijing to begin the race at 14:00.
Steady rain began to fall midway through the race.
Several riders crashed in a pileup just ahead of the final two loops up the Badaling Great Wall climb, with Gu Sung-Eun
of Republic of Korea toppling into a ditch. Two more crashes marred the action under treacherous conditions.
Natalia Boyarskaya of Russia attacked midway up the first of two finishing laps to carve out a 59-second lead over the
top of Badaling climb. Christine Thorburn of the United States led the chase on the descent and trimmed the gap to 34 seconds
for the bell lap.
Emma Pooley (Great Britain) and Guderzo surged away to swarm Boyarskaya and form a threesome with 22km to go, but the pack
regrouped under a steady pace set by the German team.
Guderzo attacked again, this time over the final summit with about 13km to go.
Christiane Soeder (Austria), Johansson, Cooke and Linda Melanie Villumsen Serup (Denmark) bridged out to open a 16-second
gap with 7 kilometres remaining.
Cooke drove home to win gold and the desperately chasing Vos led the bunch sprint and finished sixth, 21 seconds back.
Defending Olympic champion Sara Carrigan (Australia) finished 38th at 1:01 behind.
Jeannie Longo-Ciprelli (France), 49, was active throughout the race to finish 24th, 33 seconds back.