Mothers sometimes use the term “mental load” to describe the day-to-day experience of managing a home and family, an invisible workload that has received little attention in social research and in the discourses around the gendered division of labour. The aim of this study is to elaborate the experience of domestic cognitive work of a small sample of mothers from Quebec, Canada, using qualitative in-depth interviews. Through a critical grounded theory analysis, the main findings showed two overarching motivations for the mental load of mothers: (1) to manufacture household and family efficiency, and (2) to cultivate family well-being and happiness. Using social reproduction theory, I suggest a reflection of the mental load as an integral process to late capitalist reproduction, where mothers develop what I call an internalized manager to organize, plan, strategize, monitor, worry, forecast, negotiate, and remember information that mediate and protect the household against capital’s rising downward pressure on the time and resources available for workers’ reproduction.