The decline of the European fertility from the middle sixties onwards is part of a long trend of intentional restriction of births (Bardet and Dupâquier, 1986; Bandeira, 1996) known as "first contraceptive revolution" (Leridon, 1987). However, it was only with the development of modern contraception, such as the hormonal pill, that it became possible for couples to control their fertility more efficiently. This "second contraceptive revolution" changed their relation in regard to reproduction, which became a field of sequential decisions: having children or not, how many and when. In spite of this freedom of choice, European studies have stated the consistency of fertility representations and behaviours: there are few couples voluntarily childless (Toulemont, 1995; McAllister and Clarke, 1998); and the ideal norm of two children is very widespread, with the declining weight of the third child (Segalen, 1999).Portugal follows these trends, although the delay of its demographic transition (Bandeira, 1996). In fact, in the sixties, its fertility was one of the highest in Europe. Portugal was then a country where the Church had a great influence, and with an important rural social fabric. On the other hand, family planning only became a constitutional right with the democratic revolution, which also postponed modern contraceptive behaviours (Almeida, 2004). But this delay was compensated by the intensity of changes, in such a way that Portugal ends up in line with Europe in the nineties, oscillating between 1,4 and 1,5 children per women since then (Carrilho and Patrício, 2004). Portuguese studies also reveal the consistency of the ideal of two children (Almeida and Guerreiro, 1993; INE, 2001) with the ongoing decline of the ideal of three children since the seventies. Another important feature is the gap between the two children ideal and the increase of the one child offspring, which is a result of the difficulties that families have in satisfying the (growing) conditions they feel to be necessary to provide for a child (Cunha, 2006). This is a clear sign of the centrality of children to family and the importance given to their educational promotion (Almeida and Wall, 2001; Almeida, 2003). Parents give plenty of reasons for not accomplishing their fertility ideals - which often leads to the one child offspring (idem) - resulting from the difficulty in reconciling family life and labour market obligations (Guerreiro, 1998), but also the increasing postponement of the transition to parenthood in the fertility agenda (Cunha, 2006). The most recent researches on Portuguese fertility have focused separately on women and men's representations and outcomes (Wall, 2003/2005; Cunha, 2006; Almeida, 2004), but there's a lack of studies on couples as a unit of analysis, as already happens in other fields of family research (Torres, 2002). Even in the classical study of Kellerhals et al. (1982), where couples were interviewed on their reproductive expectations and behaviours, the issue of the marital negotiation of fertility was submerged under the impact of social settings. Therefore, they concluded that the professional and educational attainment of women (but not of men) were the most important predictors of couples' fertility.