Animal and human studies indicate that neonatal seizures are detrimental to the developing nervous system. This study addressed whether parameters of seizure severity and treatment were predictive of outcome and influenced the incidence of epilepsy. The outcome of babies with neonatal seizures was assessed based on follow-up examination, record review, and school performance. Epilepsy was assessed relative to developmental outcome and imaging abnormalities. There was no association between response to therapy and outcome. Neonates with mild or moderate seizure severity and decreasing severity over time, prior to anticonvulsant treatment, were more likely to have normal or moderately abnormal development than a severe outcome or death. Babies who had the highest seizure severity following treatment were more likely to have adverse outcomes. Those with normal imaging studies were more likely to have better outcome than those with diffuse severe abnormalities. Children with epilepsy were more likely to have abnormal development and imaging.