The proportion of mothers living without male partners is growing fast in Mexico, and time is a valuable resource determining their quality of life. Using the 2002 Mexican Family Life Survey (N = 1,818), the author examined the effects of coresident extended household members on time allocation by employed mothers. Results indicate that female extended kin have greater influence than male kin on the time allocation of single mothers in Mexico. Female extended household members also play more important roles in making activity time available for single mothers than for mothers with partners. This study supports the hypothesis that household extension functions as a safety net for employed single mothers facing time and material constraints in Mexico.