Adolescent motherhood has been associated with negative health outcomes for both adolescent mothers and their children in many studies. Although the link between early motherhood and disadvantage has more recently been questioned, professional understandings continue to focus on hardship and social exclusion. Social constructionism provides a critical approach to the professional constructions of adolescent motherhood. Using discourse analysis, transcripts of individual interviews with 17 New Zealand health professionals working in a variety of settings were analysed to examine the discourses used to construct adolescent motherhood. During the interviews, doctors, midwives, and nurses drew upon 'Developmental' and 'Motherhood' discourses to position adolescent mothers as problematic. The 'Developmental' discourse positions young mothers as 'adolescents' who are naive, distracted, and self-centred, and hence unable to mother correctly. The health professionals also employed a 'Motherhood' discourse that attributes certain behaviours to 'good' mothers. These discourses were drawn upon to illustrate how the characteristics of an 'adolescent' cannot be reconciled with the attributes of a 'good' mother. These constructions have implications for health care provision for adolescent mothers in New Zealand.