the purpose of this paper is to build a theoretical model about the parental behaviour of adolescent mothers. the study had the participation of twenty-one teenage mothers, aged between 14 and 18 years old at the time of delivery, and one psychologist that work with young mothers. at the moment of interviews mothers aged 15 to 32 years old. twenty-two interviews were analysed in witch seventeen of these belong to previous studies (bentes, 1996; araújo, 2000; alves, 2003; cabrita, 2004). we used semi-structured interviews that were taped and than transcribed and analysed through the grounded theory method. we found that some of the adolescent mothers reveal a maternal unavailability towards their children, reflected by lack of patience, indifference, inadequate responses, difficulty in baby care, difficulty in understanding the baby？s signals, aggressive behaviour and negative characteristics attributed to the baby. on the contrary, some adolescent mothers overcome the difficulties of adapting to maternity and reveal a maternal availability, reflected facility in baby care, concern with the child, patience, comprehension of the baby？s signals and play when interacting with their children. social support revealed as a protective factor in the maternity adaptation.