Interest is always motivating and engaging; the presence of a developing interest ensures that motivation and engagement are meaningful. However, the presence of motivation and/or engagement does not necessarily indicate that a person has interest, or that engagement is meaningful. This chapter explores what the terms "motivation" and "engagement" mean and consider their links to interest. It describes some findings from research on interest suggesting that in earlier phases of interest, interest and different types of motivational variables (goals, self-efficacy, and self-regulation) are distinct, whereas in later phases of interest they are more likely to be coordinated, develop reciprocally, and be mutually supportive. Once interest begins to develop, a person's motivation and engagement also are both positive and beneficial and will lead to developed understanding and achievement. The learning environment and tasks or activities more specifically can be adjusted to support people to make connections to them.