Although maltreatment is known to have detrimental effects on socioemotional development, the relation of those effects to type of maltreatment and child age is not clear. Most studies either focus solely on physical abuse or do not differentiate among types of maltreatment. Furthermore, most concentrate on young children. Studies of psychological maltreatment in young children indicate that physical abuse and psychological maltreatment tend to co-occur, severity of injury is not related to severity of psychological maltreatment or to developmental problems, and severity of psychological maltreatment is related to developmental outcomes. The present study investigated (a) relations among types of physical and psychological maltreatment and (b) their effect on development in an ethnically diverse sample of maltreated school-age children and adolescents. The results indicated that, as in young children, physical and psychological maltreatment co-occurred in most cases. As with young children, severity of emotional abuse was related to severity of physical neglect in school-age children; among adolescents, however, it was related to severity of physical injury. Moreover, severity of emotional abuse was related to both behavior problems and depression. The differences between the patterns of effects for school-age children and those for adolescents are discussed, as are implications of the findings for intervention.