Life skills are personal resources that can be trained and applied in a specific situation and transferred to other contexts. The growing body of research has shown that intervention programs produce positive results in learning and transferring life skills. Nonetheless, there is a need to clarify the efficacy of life skills training, namely the theoretical background of life skills interventions and how to organize the intervention programs. This paper attempts to overcome these gaps of literature by providing a conceptualization of life skills into two axes: typology (cognitive to physical continuum) and function (personal and interpersonal). Also, it is presented a theoretical model of life skills training that establishes the stages and principles of life skills acquisition, the variables that influence training, and the measures and hypotheses that can be used to evaluate the efficacy of life skills training. In sum, we clarify the actual challenges of life skills training and provide indications on how to apply and evaluate the efficacy of the intervention.