The present experiments investigated the developmental change in infants' concept of intention, and the link between intention and desire understanding in the second year. In Experiment 1, we compared 14- and 18-month-old infants' ability to differentiate between intentional and accidental actions. In Experiment 2, we compared 18-month-olds' ability to infer subjective desires for objects and their performance on the previous task. Also, performance on these theory of mind tasks was correlated with mental lexicon six months later. A developmental progression in infants' understanding of intention was observed. Surprisingly, 18-month-old infants were unable to infer subjective desires for objects. No relationship was found between infants' understanding of intention, desire, and their mental lexicon. These results have methodological and theoretical implications for research exploring theory of mind in infancy.