This review paper outlines the issues associated with the assessment of executive function (EF) in children and adolescents, and describes the developmental profile of executive processes across childhood. At the outset, EF is defined, and cognitive and behavioral impairments associated with executive dysfunction (EDF) are described. A developmental model of EF is proposed incorporating four discrete but inter-related executive domains (attentional control, cognitive flexibility, goal setting, and information processing) which operate in an integrative manner to enable "executive control". Characteristics that constitute traditional EF measures are discussed, as are the problems associated with test interpretation. The ecological validity of EF tests and neuropsychological assessment procedures are examined, and adjunct methods of measurement are presented to enable a more comprehensive and valid assessment of EF. Based on developmental and normative studies, the maturation of executive domains is mapped. Attentional control appears to emerge in infancy and develop rapidly in early childhood. In contrast, cognitive flexibility, goal setting, and information processing experience a critical period of development between 7 and 9 years of age, and are relatively mature by 12 years of age. A transitional period is thought to occur at the beginning of adolescence, and shortly after "executive control" is likely to emerge. In order to confirm our current understanding of EF development and further enhance our understanding of brain-behavior relationships, longitudinal studies incorporating structural and functional neuroimaging are required.