A pool of 75 items relating to family functioning was created and piloted in a sample of 12-18 year olds (N = 673). The responses were subjected to an exploratory factor analysis which indicated the presence of three significant latent traits. The results were then used to inform the development of a rating instrument with five subscales labelled "Nurture, Problem Solving, Expressed Emotion, Behavioural Boundaries and Responsibility". These demonstrated high levels of internal consistency (Cronbach's alphas 0.70-0.81), high test-retest reliability (rho = 0.70-0.82), varying degrees of intercorrelation (rho = 0.18-0.75) and significant associations with family functioning as defined by the McMaster Family Assessment Device (p less than 0.0001 in all cases). This novel instrument is a promising tool for use in both clinical practice and research.