This study investigated associations of low-income working mothers' daily perceived workload and their reports of their own mood and their interactions with their young children. Sixty-one mothers were asked to report on their workload, mood, and interactions with their preschool-age children every day for 2 weeks (N = 520 work days). Low-income mothers reported significant day-to-day variability in workload. The results revealed a curvilinear pattern of negative work-to-family spillover: Both lower-than-average and higher-than-average workload days were associated with increased negative and tired mood, decreased positive mood, and increased harsh mother-child interactions. Although both younger and older mothers experienced a curvilinear pattern of spillover to daily mood, younger mothers in the period of emerging adulthood also experienced spillover to mother-child interactions, perhaps because they are still learning how to balance work and family demands. Both high and low workload are salient stressors in the daily lives of low-wage working mothers. © National Council on Family Relations, 2013.