By considering the important role that boredom tolerance-proneness seems to play in various forms of adult psychopathology, the authors wondered whether working on this emotion in children with disorders referable to the externalizing spectrum could affect specific performance related to sustained visual attention. The aim of this pilot study is to explore the feasibility and effects of applying a specific intervention for boredom regulation in infants and primary school children. The intervention has been conceived as a sequence of exercises based on mindfulness and metacognition whose goal is to train children’s tolerance to boredom that is the state of perceiving the external environment as monotonous, repetitive, with low levels of stimulation associated in turn with an affectivity characterized by a poorly pleasant emotional state. The data show good adherence to treatment and a significant improvement in selective and sustained attention at the end of the treatment. Our findings are encouraging and demonstrate that the proposed intervention can be a reliable intervention to be integrated with other approaches for the treatment of externalizing disorders in children.