Households in the affluentWest have become an important target of government andNGOcampaigns to encourage more environmentally sustainable behaviours, but there has beenlittle research into the gender implications of such policies. This article investigates therole of gender and time in the sustainability practices of six heterosexual householdswith young children, committed participants in the Sustainable Illawarra Super Challengeprogramme in 2009. Women spent more total time on sustainable practices, and did somore often.Men’s contributions relatedmostly to gardening and transport, in longer blocksof time. In these households, sustainability became a highly gendered practice becauseof the different roles in homemaking. Women resisted constructions of themselves asbeing closer to nature, and shouldered expectations of sustainability as part of their roles asmothers and household managers. They experienced time as overlapping and fragmented,with no distinction between work and leisure. Men contributed to sustainable practicesmainly through activities understood as leisure, in longer blocks of time. Our temporalitylens also illustrates the gendered ways that old practices become deroutinised andnew practices reroutinised. While men were often responsible for the labour and upfronttime required to start or research a project, the responsibility of everyday implementationand habit-changing commonly fell to women. These findings illustrate how genderedanalyses help identify both opportunities for, and constraints against, change towardssustainability. Opportunities include the strong connections between both mothers’ andfathers’ understanding of good parenting and the importance they attach to householdsustainability. Constraints include the temporal challenges faced by households, and howthese interact with wider structural and labour roles..