We investigated longitudinally the development of attention in two free-play tasks and the relation between attention in those tasks and language ability in toddlerhood. We observed developmental differences in attention from 9 and 31 months both as children investigated a single object and as they investigated multiple objects. Attention in these contexts at 9 months was differentially related to vocabulary at 31 months, but concurrent measures of attention at 31 months were not related to vocabulary at that age. The results are discussed in terms of the potential processes guiding the relation between attention and cognitive outcome and the development of endogenous control of attention. (Contains 3 tables.)