Five aspects of the psychological assessment of children are considered. First, the hypotheses of assessment are examined, with attention to the role of the scientist-clinician, the nature and the social and personal determinants of development, and the ego as the object assessment. Second, methods of data collection are surveyed, including techniques based on samples of manifest behavior, on subjective reports, and on associative behavior. The nature and evaluation of assessment techniques are also considered. Third, procedures in assessment are discussed; they include the assessment milieu, referral, and the assessment procedure. Fourth, analysis of the assessment or specifications of the ego functions are treated in the following areas: analysis of perceptual motor and cognitive development, analysis of affect development, assessment of conative development, assessment of social development, analysis of ego functioning and identity formation, and reporting the assessment. Fifth, assessment for psychotherapy and for physiological and environmental interventions is explained. Seventy cases are cited throughout the text. (JD)