In a world that offers children abundant activities from which to choose, understanding how to motivate children to engage longer in productive activities is crucial. This paper examines how the offered assortment size affects children’s engagement with their chosen options. In the first study, I show children prefer to choose from a larger set even though they think doing so is more difficult. Then, in studies 2 and 3, four- to five-year-old children choose from either a small set (two options) or a large set (six or seven options). In study 2, children choose a book to look at and I measure how long they look at it. In study 3, children choose a game to play with and I measure how long they play. Children spend more time looking at the book and playing with the game they choose from the small versus the large set. In contrast, the size of the choice set does not affect food consumption. Such findings contribute to our understanding of young children’s decision-making and have important implications for determining the optimal assortment size to offer children to increase engagement with desirable activities.