The process of household decision-making encompasses a core question that lies at the heart of gender inequalities: the gender division of labour. The links between general household decision-making process, gender division of labour and gender inequalities are the focus of this research project which aims at bringing new theoretical as well as empirical insights on these issues. Now that time use surveys are made available in more and more countries, international comparisons seem to reveal a new model of labour division between men and women. The picture emerging is that besides a now massive female participation in the labour market in most developed countries, the household division of labour remains highly gender-specific. Research consistently has shown that women still do the largest share of unpaid labour within households. If an economist expects to explain this, at least partially, by the observed difference between men's and women's wages or educational attainments, these variables happen to have a small impact, if any, on the intra-household allocation of labour. Consequently, the gender division of labour, if not terra incognita, still remains a mystery for the economist. Beginning with the matching of partners, examining in depth empirically the key variables explaining the observed gender labour division within households and the role of childbirths and childcare in the differentiation of male and female trajectories, and finally further developing the modelling of the household decision-making process on the basis of the empirical observations now permitted by the availability and comparability of more and more time use surveys, as well as matched employers/employees datasets, this research has the ambition to participate, with the economist's tools, in finding out the roots of gender inequality.