Although laboratory studies have examined the development of children's prospective memory (PM) and the factors that influence its performance, much less is known about children's PM performance and development in their everyday life. The current study used an online parent diary report approach to examine American 2- to 6-year-olds' PM successes and failures. In an initial session, 206 parents completed a series of questionnaires on their child's memory and cognition. For the next four days, parents reported instances of PM successes and failures and answered questions about a number of task factors (task motivation, importance to the parent and child, who assigned the PM task, task typicality, and parental assistance). We found that: (1) parents reported children as young as 2 years old had PM successes in daily life and there were no age differences in the number of reported PM successes and failures, (2) parents reported more PM successes than failures, and (3) several factors influenced the likelihood of children's success in everyday PM tasks, including child motivation and task importance to parents, whereas task typicality and parental assistance were related to PM failure. Finally, we explored the domains of PM successes and failures as well as the type of assistance that parents provided. These results are discussed in relation to past findings of children's PM in laboratory and naturalistic settings. Parent diary-report methodology is a feasible and efficient alternative to naturalistic laboratory tasks to examine young children's PM in everyday life.