The Kenyan beat Ethiopia's Amane Gobena by 17 seconds. American Elva Dryer was third in 34:01.
The men's annual Memorial Day race was much closer as Ridouane Harroufi of Morocco passed Ethiopian Solomon Tsige Asfaw on the downhill leading to the finish line at Folsom Field and used a strong kick to win in 29:52, beating Asfaw by six seconds. Worku Beyi of Ethiopia was third in 30:04.
Kiplagat, who also won the Bay to Breakers 12K in San Francisco and the Lilac Bloomsday 12K in Spokane, Washington, this spring, powered past Gobena and her teammates, Dire Tune and Teyba Erkesso, as the leaders exited the stadium and headed toward the race's midpoint.
None of the Ethiopians could catch Kiplagat, who ran the remainder of the race well clear of the field.
Wind and warm weather resulted in the slowest winning time in the race since 1988.