This paper describes 59 patients, 3 months to 16 years of age, who were seen consecutively in the same center for cerebral arterial infarction. It focuses on the mechanism of stroke. The pathophysiologic process could be established for 78% of the children. Arteriopathic stroke (31 patients, or 53%) was the most common. The arteriopathies were either progressive (moyamoya in 4 patients, or 7%) or nonprogressive (27 patients, or 46%). The latter form occurred in two patterns: dissection of cervicocephalic arteries (12 patients, or 20%) and transient cerebral arteriopathy of unknown origin but probably angiitis (15 patients, or 25%). Cardiac or transcardiac embolic stroke occurred in 12% of the series and systemic diseases in 14%. There was a favorable outcome in 70% of patients having stroke due to nonprogressive arterial disease and stroke due to unidentified mechanisms. In contrast, only 26% of patients with embolic stroke, systemic disease, or moyamoya had a favorable outcome. Recurrences were more frequent and severe in this latter group. It is concluded that it is important to determine the mechanism of childhood stroke, because it strongly influences outcome, the recurrence risk, and treatment choice.