The aim of this study was to evaluate computer-based compositions by children with and without prior experience of formal instrumental music tuition (FIMT). Three different evaluations were employed involving music specialist and non-specialist teachers, the children themselves, and expert ratings of melodic and rhythmic repetition and development. Participants were 32 children (aged 10 years) who had a minimum of two years of FIMT (n=16) or no prior experience of FIMT (n=16). Both groups were invited to compose a "piece" that "sounded good to them" using a specially designed computer-based composition programme. Results indicated that specialists and non-specialists did not differentiate between children with or without FIMT in their ratings of overall achievement. However, a factor analysis of the teachers' ratings of 15 specific characteristics revealed one factor for the non-specialists and three factors for the specialists. Specialist teachers' ratings of factor two, which was interpreted as "technical complexity", indicated higher ratings for the children with FIMT than those without FIMT. Children with FIMT gave higher self-evaluations for "how good their composition sounded" than children without FIMT. Ratings of musical parameters revealed a greater use of melodic and rhythmic development by children with FIMT. Implications for music education and proposals for future empirical work are discussed.