Summary: Multiaxial classification system development (organising important and relevant clinical factors under multiple headings or 'axes') has a long history stretching back to the 1940s. The World Health Organization supported the development of a multiaxial system of classification for children from the 1960s and in the 1990s produced a comprehensive multiaxial system which could be used with ICD-10. Using the multiaxial approach provides for an atheoretical framework that can integrate factors from within the child and the environmental influences on the child. This article presents a variety of ways in which the ICD-10 multiaxial framework can be extended from its classic usage to provide clinicians with valuable tools to assist in a biopsychosocial clinical assessment. Using the multiaxial system in an extended format allows a more comprehensive diagnosis and planning of treatments and is helpful in the training and teaching of juniors. It is also useful in evaluating responses to medication when it is combined with a chronological analysis and can provide other useful ways of integrating information relevant to understanding clinical cases
