From Piaget's early work to current theory of mind research, young children have been characterized as having little or no awareness of their mental activity. This conclusion was reexamined by assessing children's conscious access to visual imagery. Four-year-olds, 6-year-olds, and adults were given a mental rotation task in the form of a computer game, but with no instructions to use mental rotation and no other references to mental activity. During the task, participants were asked to explain how they made their judgments. Reaction time patterns and verbal reports revealed that 6-year-olds were comparable to adults both in their spontaneous use and subjective awareness of mental rotation. Four-year-olds who referred to mental activity to explain their performance had reaction time and error patterns consistent with mental rotation; 4-year-olds who did not refer to mental activity responded randomly. A second study with 5-year-olds produced similar results. This research demonstrates that conscious access to at least 1 type of thinking is present earlier than previously recognized. It also helps to clarify the conditions under which young children will and will not notice and report their mental activity. These findings have implications for competing accounts of children's developing understanding of the mind and for the "imagery debate".