Childhood stroke is increasingly recognized as a major cause of childhood morbidity and mortality; however, limited information exists regarding neurobehavioral sequelae. Executive function (EF), important for problem solving, reasoning, social awareness, and adaptive behavior, may be particularly vulnerable to early brain lesions such as stroke, due to its protracted development. This study investigated: (i) the impact of childhood stroke on EF; and (ii) the impact of lesion size on EF outcome. Twenty-eight children diagnosed with stroke at least 12 months prior to assessment were recruited. Neurobehavioral assessment focused on cognitive and behavioral aspects of EF. Lesion volume was determined from standard ratings of brain pathology based on magnetic resonance imaging (MRI) scans. Deficits in cognitive aspects of EF were detected in attentional control, cognitive flexibility and information processing. Difficulties in behavioral aspects of EF were most striking, with problems identified across a wide range of behaviors. Lesion size impacted on EF, with large lesions (greater than 25% of brain volume) proving the most detrimental.