The increasing interest in children and young people as composers, as evidenced by the growing literature on the subject in recent years, has tended to overlook at least one important aspect of young composers' development: their sense of tonal thinking, its emergence and consolidation. This article traces these characteristics through the compositions of one boy, showing how he ‘progressed’ from pre-tonal operations to fully-established tonal procedures. The discussion of his development is deliberately limited to the examination of harmonic thinking, which manifests itself before long(er)-range tonal planning (in the form of tonality or key schemes) becomes a focus of concern.