On this site, there are interactive tools that allow you to view developmental milestones (social/emotional, cognitive, & language) at each age and stage and a checklist to track your own child’s development.
http://www.cdc.gov/ncbddd/actearly/milestones/index.html
View the video Baby Steps, describing early milestones at: http://www.cdc.gov/CDCtv/BabySteps/