Fifty-nine children with juvenile idiopathic scoliosis have been reviewed. In six of eighteen who had no treatment the curvatures did not increase over eighteen months or more, while in twelve they increased at a median annual rate of six degrees. The pattern and magnitude of the curvature and the age at diagnosis could not be used accurately to predict progression. In forty-two patients progression occurred and Milwaukee brace treatment was begun, thirty being managed with periods of part-time wear. The median correction was 13 per cent. Serial measurements of the rib-vertebra angle difference (RVAD) were useful to predict a tendency to progress. Part-time wear of the brace was successful in cases where the RVAD values fell towards zero or became negative with treatment. Sixteen patients required surgical treatment; all had high positive RVAD values. However, with the plan of brace treatment outlined, part-time wear controlled many of the curvatures.