The study examined the effectiveness of PRERAYMI (Promoting Responsiveness Emotion Regulation and Attachment in Young Mothers and Infants) attachment-based intervention programme aimed at adolescent mother-infant dyads. The intervention used video-feedback and developmental guidance to promote maternal mind-mindedness and sensitivity. 32 adolescent mother-infant dyads in the intervention group were compared to 12 adolescent mother-infant dyads in the control group. Maternal mind-mindedness and maternal/infant styles of interaction were evaluated, at the pre-treatment (infant 3 months) and at the post-treatment (infant 9 months). The results indicated the effectiveness of the intervention in enhancing mind-mindedness, with more mind-related comments and fewer non-attuned mind-related comments, maternal sensitivity and infant cooperative behaviour, and in reducing maternal controlling behaviour, in the intervention group. Changes in mother/infant interaction styles or in mind-mindedness in the control group were not detected. The attachment based medium term intervention helped to improve adolescent mother-infant relationship, which is otherwise potentially at risk.