The purpose of this study was to characterize the behavior of 2-, 3-, 4-, and 5-year-old children engaged in improvisational musical tasks. Ten subjects from each of the four age levels participated in the 4-year investigation, which lasted until the 2-year-olds reached 5 years of age. Children met individually with the investigator for 15 minutes at a time; each session involved three improvisational phases. During phase one, free exploration, each child was given a free opportunity to explore the xylophone. During phase two, guided exploration, the children's explorations were directed through two improvisational tasks: "let's pretend" (to evoke different emotions) and "conversations." During phase three, exploratory improvisation, the child was asked to improvise a melody while the investigator played a 24-measure bordun accompaniment. All sessions were recorded on cassette tape, and notes were written after each session. Results lent support to prior research indicating that characteristics of children's improvisations change in relation to chronological age. Improvisations were grouped into three stages. Stage one, motor energy, was characterized by plodding and accented durations. Stage two, experimentation, was characterized by the child's experimenting with many phrases and combinations. Stage three, formal properties, was characterized by repetition, larger formal structures, and decentered perception. Results were discussed in terms of implications for teaching practice. (CB)