There are definite milestones that speech-language pathologists use in assessing children. Believe it or not, we can evaluate children even younger than two if there are concerns. Typically, children have at least 30-40 expressive words by the age of 2. Children that age should also be able to follow two step directions with repetition. If you are concerned, share your toddler's skills with your pediatrician but also pursue an evaluation with a speech-language pathologist (ASHA.org).