As shown by recent studies, specific dimensions are carried out in the intersubjective experience of mother-child relationship and seem to be essential in shaping these dynamic interactions and the child development. In particular, one aspect that is still unexplored is whether and how representational dimensions of mother and child play a determinant role in the quality of mother-child relationship and in the child development. The goal of this project is to understand the development, stability and change of mother child interaction in the first two years of life, and to stimulate research into the mechanisms underlying this developmental trajectories. A sample of middle class Switzerland (Canton Ticino) women will be recruited during their third trimester of pregnancy from maternity wards and will be followed until two years of children’s age. On the mother’s side the analysis will be focused on: her "states of mind" of past experiences of attachment (AAI, Main et al., 1985) and of current relationship with the child (PDI; Caregiving System Rating Scales, George & Solomon, 1989); on her capacity to envision mental states in self and others (Reflective Functioning Scale, Fonagy, 1989) and on the marital relationship (Dyadic Adjustment Scale, Italian version Gentili et al., 2002), and the support perceived from the mother or in its role of mother whom of companion (Support Perceived Questionnaire, Cook et al., 2006). Also, will be evaluated several aspects of child developmental functioning, such as: temperamental, cognitive, motor, behavioural, social and emotional competencies. Furthermore, will be assessed the infant attachment quality with the mother (Strange Situation Procedure, Ainsworth, 1978) and, also, the quality of mother-toddler interactions during 2nd year of life (24 Months mother-Child Interaction Scales, Jacobvitz et al., 2004). The innovative and relevant contribution of the project relies in the possibility to monitoring and evaluating over time and in crucial phases in the development of intersubjectivity, how specific indicators, individual and/or relational, emerge and interact within the mother-child relationship; secondly, a longitudinal survey would provide an opportunity to follow the long-term effects exercised on the development of the child by maternal behaviour and her mental representations of attachment. We will concentrate on regulatory factors internal to the relationship, and, especially, on risk factors (difficult disruptive affective regulation, infant temperament, maternal depression), considered as a possible source of impairments in the developmental path.