According to the Center for Disease Control and Prevention (CDC), a preschooler is a child between the ages of 3 and 5 years old. However, there is no definitive answer to when a child should start preschool, as age and entry criteria will vary at different preschools. Some preschools enroll children as young as 2.5 years old, while others take children at four. The average starting age is between three and four years old. It is important to note that age should not be the only determining factor when deciding when to start preschool. Parents should also consider their childs individual readiness level, including their developmental milestones, social-emotional skills, and academic preparedness.