Whilst literature exists describing prevalence and theories about mechanisms of development of deformity, there is a distinct lack of research that examines how deformity can be measured despite it being an area of identified need. This study established the inter- and intra-rater reliability of the Goldsmith Index of Body Symmetry and examined the relevance of the information it provides within the context of a comprehensive postural assessment for individuals with cerebral palsy in conjunction with a commonly used clinical assessment ... Results demonstrated that high index levels were not exclusively associated with people with windswept deformity. Postural patterns of windsweeping, frog leg (abducting) and scissor (adducting) postures and hip extension were found to occur in all categories, suggesting that asymmetry is not confined to one particular postural pattern. Clinically observable changes were identified through comparison of the supine evaluation and index scores. The flexibility of postural components (or the ability to correct asymmetry) in a supine position for the SD categories demonstrated wide variation. However, subjects in the 3+SD groupings had fixed scoliosis and the majority (83%) also had fixed pelvic obliquity and rotation. All other subjects up to the 3SD category had flexible pelvic obliquity and rotation. No definitive differences in postural components between groups were identified in sitting positions, which was attributed to the influence of gravity on the body in an upright posture. Examination of sitting ability and index level did not demonstrate any relationship, suggesting that greater independence in sitting is not necessarily associated with a lower Goldsmith Index. The study highlighted that assessment of posture is complex, and that no single tool provides the answers required to manage a person’s posture. It demonstrates the need for clinicians to be aware that subjective clinical assessment may not be sufficient to adequately assess and detect changes in posture, and that the Goldsmith Index of Body Symmetry provides objective data that can be used as a powerful adjunct in interpreting clinical assessment and supporting the evaluation of clinical interventions.