The close association of spinal deformity with growth suggests that scoliosis may be a developmental response to perturbation of growth processes. Developmental criteria in 327 girls with late-onset idiopathic scoliosis were examined. Age at diagnosis correlated with apex (P=.002), Cobb angle (P=.006) and with age at menarche (P=.008). For left-right asymmetry, comparison of dermatoglyphics in 114 normal girls and 164 with AIS showed that in AIS there was increased directional asymmetry. When those with AIS were divided into school screening referrals (N=86) and others (N=78), the latter showed a significantly greater variance about the mean (P=0.0) suggesting that they form different subgroups of the population, with decreased developmental stability. These findings may be interpreted to indicate cephalo-caudal and left-right gradients and significant differences in the control of development in AIS.