At this age, your child should be putting two words together ("Go car?") and following two-step commands ("Get your sweater and come to the car"). She may over-generalize — call every man "Dad," for example — or be overly specific (only her Rover is a "dog"), but she'll get it all sorted out. Pronouns can be particularly tough; listen as she first calls herself by her name, then "me," and finally "I."
Since language development varies hugely from child to child, many parents wonder when to worry about their child. In addition to the milestones mentioned above, 2-year-olds should be learning more words every day and naming some pictures in books. If not, be sure to mention your concerns when you take her in for her checkup.
Also be sure to tell your health care provider if your child can't be understood by strangers half of the time, doesn't respond to her name, loses any language skills, or reaches a "skill plateau" that lasts more than two months.
Learn more about language milestones.