There is a rich debate surrounding the causes of women's heterogeneous work-life orientations and strategies. This article focuses on the debate between postmodern individualistic approaches and gender approaches that emphasise the pervasiveness of socio-structural factors. After offering a profile of Spanish women in the twenty-first century, we present the results of qualitative research based on 30 semi-structured interviews with working mothers from different social backgrounds. We discuss Hakim's 'preference theory' by exposing how social class shapes Spanish working mothers' work-life attitudes and behaviour and how these further change over the life cycle or as a result of changing contexts.