The usage of high-quality learning applications (apps) at home may increase children's mathematical and literacy competencies. This approach was tested in a family intervention study. Intervention families (n = 302) in two German cohorts (N = 500; M (SD)[subscript age] = 61.0 (4.6) months; n[female gender symbol] = 302) received tablets with newly developed learning apps focusing either on mathematical or literacy learning for every-day usage at home across half a kindergarten year. Compared with two control groups with and without tablets, children in the intervention groups significantly enhanced their specific competencies (n[superscript 2] = 0.03-0.10). Higher app usage was associated with greater gains ([delta]R[superscript 2] = 0.01-0.02). Consequently, an easy-to-apply app-based intervention supports children's development of cognitive competencies and helps prepare them for school.