This chapter discusses the development of subnormal performance in children from a motivational-interactionist perspective. Most developmental theories presuppose that the growth of the child's adaptive capacity is based on the increasing organization and differentiation of mental and behavioral structures, progressively leading to growing self-regulation and independence of action from immediate external stimuli. The development of self-regulation is accompanied by an increasing sense of self-efficacy and motivation to initiate and maintain task-focused activities related to new environmental challenges. The characterization of the ideal scaffolding process implies the possibility of several less optimal alternatives based on the fact that the adults do not sufficiently pay attention to a particular child's changing needs during the scaffolding processes and cannot adjust their activities accordingly. It is suggested that children high in ego-defensiveness may be motivationally more vulnerable to the new demands of learning to read than task-oriented children, and this vulnerability in turn influences their cognitive development.