Human development implies deep changes in cognitive, attentional, emotional, and behavioral skills. Therefore, Mindfulness-Based Interventions (MBIs) should be adapted in terms of dose, frequency, kind of exercises, assessment methods, and expected effects regarding the abilities and limitations of each developmental period. The present review seeks to describe and compare MBIs characteristics, assessment methods, and effects in youth between 3 and 18 years old considering four developmental periods. A systematic review was carried out including experimental primary studies published during the last five years. Results show that the frequency of the sessions and program duration varies widely. Differences were observed in instructors’ training and in assessment strategies. Discrepancies were observed regarding the effects of MBIs both within and between periods in cognitive, socio-emotional, symptoms, and mindfulness variables. Consistency was observed in prosocial behaviors for preschoolers, and in emotional and behavioral problems and hyperactivity in ages between preschool and early adolescence. Nevertheless, it was impossible to compare most results and determine consistency or discrepancy due to the lack of studies. Regarding mindfulness, it is defined and assessed in different ways in each period. Orientations are suggested to move from a compartmentalized view of isolated MBIs, towards an integrative perspective that allows tracing developmental trajectories for mindfulness and other key cognitive and socioemotional skills for children and adolescents.