Using the framework of mastery motivation, this chapter introduces the complex construct of motivation and highlights its importance for children’s learning. As demonstrated for typically developing children, mastery motivation has been shown to be an important predictor of academic outcomes for children with Down syndrome. Although deﬁcits in motivation are sometimes presumed to be part of the learning and behavioural proﬁle of Down syndrome, most of the empirical evidence shows no differences in mastery motivation when children with Down syndrome are compared to typically developing children of the same developmental level. By contrast, parent reports consistently suggest that children with Down syndrome have difﬁculties with motivation, possibly because parents are making comparisons with their child’s sameage peers rather than with children of similar developmental levels. Drawing on a wider research base, the chapter considers the child and environmental characteristics that inﬂuence mastery motivation. Children with Down syndrome and other developmental disabilities experience a range of health, sensory, and motor difﬁculties that may interfere with their motivation for mastery. Children’s beliefs about their own ability, the attributions they make for success and failure, and their expectancy about future success are all likely to impact on approaches to learning tasks. In addition, the difﬁculties many children with Down syndrome have in relation to self-regulating their attention, learning, and behaviour are likely to undermine their mastery motivation. Although some of these individual characteristics are intrinsic to the child, many are inﬂuenced or modiﬁed by the contexts in which children live and learn. Within these contexts, of particular importance is giving children the opportunity to engage with cognitively stimulating activities. Other important environmental inﬂuences on motivation are adult attitudes and expectations, structure, positive reinforcement, and support for child autonomy. The chapter concludes with strategies for promoting and sustaining children’s interest in learning, and recommendations for future research.