Women remain underrepresented in politics in the majority of democracies around the world. Part of this gender gap is due to not only the decision to run for office in the first place, but gender differences in elected politicians’ desire to continue in their post (static ambition) or run for a higher office (progressive ambition). In this study, we explore one potential mechanism which could influence politicians’ static and progressive political ambition: the mental load. Women continue to take a “second shift” of unpaid labor in the household, and part of this involves not only the physical work of caring for children and relatives and taking care of other household work, but the mental work of anticipating household needs, making decisions, and monitoring progress. We argue that women politicians are more likely to carry the domestic mental load compared to men politicians, and that this added cognitive burden can reduce interest in further political ambition. To test our argument, we rely on a survey experiment fielded to local councillors in England which manipulates whether respondents are asked to think about their own domestic mental loads before answering questions about political ambition. The results offer new evidence about the relevance of household inequalities, and the often-invisible mental load, in political life.