By 1 year does not:

• Understand simple questions
• Look at familiar people when named
• Maintain eye contact with speaker
• Begin to imitate words
• Say 1–2 words independently

By 2 years does not:

• Identify basic body parts
• Understand simple commands like “give me”  without gestures
• Demonstrate action words (e.g., eat)
• Speak using 1–2 words at a time
• Use new words frequently; use at least 50 words

By 3 years does not:

• Use short sentences (e.g., “Car go up”)
• Relate experiences verbally
• State own first and last name
• Count to 3

By 4 years does not:

• Understand comparisons
• Make inferences
• Use short but grammatically correct sentences

By 5 years does not:

• Understand complex directions
• Understand concepts
• Use complex sentences
• Respond to “why” questions with a reason

By age 3 years cannot:

• Be understood by family and/or caregivers
• Correctly produce vowels and sounds such as p, b, m, and w  in words
• Repeat when not understood without becoming frustrated

By age 4 years cannot:

• Be understood by individuals with whom they do not associate regularly 
• Be understood by family and/or caregivers
• Correctly produce t, d, k, g, f
• Be asked to repeat without becoming sensitive

By age 5 years cannot:

• Be understood in all situations by most listeners
• Correctly produce most speech sounds
• Be asked to repeat without exhibiting frustration