The prevalence of primary and secondary enuresis was examined longitudinally in a large sample of New Zealand children at ages 5, 7, and 9 years. While the prevalence of primary enuresis fell over time, secondary enuresis increased in prevalence between 5 and 7 years. There were no sex differences. An examination of some of the developmental and background characteristics of the sample indicated that enuresis was not associated with neurodevelopmental delay or 'psychosocial' factors. However, there were strong, long term associations between secondary enuresis and behavioural deviance. The behavioural results suggested that behaviour problems did not arise as a consequence of enuresis, but rather preceded it.