When should a toddler speak in sentences?

Most developmental milestones in toddlers are obvious. We know, in no uncertain terms, when our toddlers can walk, when they can run, and when they can scribble. But one of the most talked about milestones, speaking in sentences, is very poorly defined. One mom might say that her toddler speaks in sentences because he puts together a two-word phrase, but others others define "speaking in sentences" as routinely engaging in grownup-like discussions.

It's hard to say when a toddler should be able to speak in sentences, since it's a milestone that develops gradually and has several definitions. Here are some guidelines about when toddlers should begin speaking in sentences.

1. Toddlers put two words together between 20 and 30 months of age. At around your child's second birthday -- and usually between his 20th and 30th month of life -- he'll begin putting two words together into simple phrases and pre-sentence structures. These phrases may be primitive sentences, like "want ball," or simple descriptions, like "big dog." If your toddler doesn't piece two-word phrases together by two and a half years of age, he may need to be evaluated for a speech delay.

2. Toddlers' sentence-lengths progress rapidly in the third year and fourth years.

Between your toddler's second and third birthdays, his sentence length will increase rapidly. An average 2-year-old's average utterance length is 1.91 words, while most 36-month-olds speak in sentences averaging 3.16 words in length. By age 4, preschoolers speak about 4.5 words per sentence -- just a little below the average sentence length of older children and adults.

3. Toddlers should speak in three-word sentences by age 3. By the time your child is 3 years old, she should routinely speak in sentences containing three words or more. Although most toddlers do use fairly primitive, short sentences at age 3, they should readily combine several words at a time. Watch for rapid advancements in grammar and sentence structure during the preschool stage.

4. Phrases and sentences become more complicated over time. Toddlers usually master the past tense some time between 26-48 months of age, and the suffix "-ing" some time between 19-28 months. An average toddler also masters the article "a," "an," and "the" between 28 and 46 months of age. Although there is obviously a broad normal range of grammar acquisition, you should notice your toddler's sentences growing in complexity month by month.

5. Watch for signs of developmental delays. In some cases, a toddler's inability to speak in sentences may be a sign of a hearing problem, learning disability or speech disorder. Be sure to consult a professional if your toddler doesn't form two-word phrases by two and a half, three-word sentences by age 3, and four- to five-word sentences by age 4. If your child does have a delay in her language development, early intervention can help to mitigate long-term problems.

This milestone list offers more information about toddler language milestones. You can learn more about toddler sentence length by clicking here.

Check out related content by this writer:

What to Expect: Your Toddler's First Speech Therapy Session

Overcoming Pronoun Reversal in Toddlers

Echolalia in Toddlers: Normal, or a Symptom of Autism?