The aims of this research were to identify the ways in which parents may most constructively support their children's musical development, and to ascertain whether styles of parent-teacher and parent-pupil interaction would influence the extent to which parents engage in different types of supportive behaviours. A model of parent involvement as comprising behavioural support, cognitive/intellectual support and personal support was applied to a sample of 337 parent-pupil-teacher trios, in the context of individual violin instruction. A typological approach was taken; using a quantitative survey that measured interpersonal interaction behaviours, as well as learning outcomes, six distinct categories of parent-pupil-teacher interaction types in instrumental learning were identified. The three categories of parental support were compared across these interaction types. The extent to which parents engaged in various types of support was found to vary according to interpersonal relating style, and the interaction types in turn were found to impact on learning outcomes. Learning outcomes, including enjoyment of music, motivation, self-esteem, self-efficacy and personal satisfaction with music lessons, were found to be enhanced when parents: (1) elicited their children's views regarding appropriate parental involvement, (2) negotiated with their children over practising issues, within parameters set by the teacher, (3) provided a structured home environment for practice, (4) took an interest in promoting good teacher-pupil rapport, (5) communicated with the teacher in relation to the child's progress and (6) remained as a supremely interested audience. (Contains 8 tables and 2 figures.)