Under "Preschool Development," you will find developmental milestones for preschool age children.  These lists were created from various websites, and credit is given on each page. 

According to Kyla Boyse, R. N., "Developmental milestones are a set of functional skills or age-specific tasks that most children can do at a certain age range.  Your pediatrician uses milestones to help check how your child is developing.  Although each milestone has an age level, the actual age when a normally developing child reaches that milestone can very quite a bit."  Any concerns that you have should be addressed with your pediatrician.