21-Month-Old: Milestones and Development

Last Updated: 
November 6, 2023
 | 
9
 minutes read
Written by
Amanda Kule
Parent Contributor
Medically reviewed by
Arik Alper, MD
Pediatric Gastroenterologist and Aerodigestive Specialist

Another month closer to having a two year old! 21 month developmental milestones may seem like ones you’ve experienced over the last few months, but as your toddler approaches their second birthday we promise—they’ll continue to surprise you.

At 21 months your little one has endless energy, big feelings, and independent moments. It is normal for parents to wonder if how your child is behaving or developing is typical, which may feel overwhelming. 21 months old can look different for everyone, which is why our team of pediatricians and sleep consultants put together this guide on what you may expect for 21 month old milestones.

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Life With a 21 Month Old

21 month old milestones can be both joyful and challenging.

At this age, your child maybe a whirlwind of energy and curiosity, running around and exploring the world like they’re seeing everything for the first time—which often, they are! Their language skills are also rapidly developing, and they're eager to communicate, even if it's through a combination of words, sounds, and gestures. Their imagination is also starting to run wild, making playtime even more exciting.

The daily routine at this age may also be an ever-evolving adventure. Even if your routine seems pretty locked, a 21 month old’s newfound independence may lead to some speed bumps. Whether it be insisting on doing thing “by myself,” refusing bedtime, or only eating what and when they want, frustration and occasional tantrums can run amok for everyone.

However demanding, the laughter, hugs, and moments of wonder make every day with your 21 month old incredible—and remember, time is fleeting so soak it all in!

Sleep and Nap Tips for 21 Months

With independence being a notable 21 month old milestone, sleep may be one of the things that they decide is no longer for them.

If you’re finding that your 21 month old is rejecting naps or bedtime, or trying to escape their crib, here are some tips for keeping their sleep on track.

  • Check how much daytime sleep they’re getting: They should have completed the 2-to-1 nap transition around 15 months, and at this point should be napping one time a day. They should be getting about 12-14 hours of total sleep, with 2-3 hours in the day and 10-12 hours overnight. Keep in mind that too much daytime sleep can keep them up at night!
  • Lower the crib: If you haven’t already, lower the crib to make sure your little explorer isn’t able to easily climb out if they decide they don’t want to go to sleep.  
  • Don’t let them skip naps: Even though 21 month olds may resist a nap at this age, sleep consultants recommend you try to not skip naps until they’re at least three years old. If they do end up skipping a nap, try for an earlier bedtime. More on nap transitions here  
  • Keep your bedtime routine consistent: Doing the same routine every night cues to your toddler that it’s time for bed and helps them settle. The Smart Sleep Coach app can remind you when it’s time for bed and make sure their schedule stays on track.  
  • Curb the FOMO: The onset of separation anxiety can be well before your toddler’s first birthday, but it continues to develop as they reach age two. At around 21 months the concept of logic is growing by the minute, which means that when you leave the room they know you are doing something else, somewhere else. Try playing “peek-a-boo" and encourage independent play to deal with their Fear Of Missing Out. Reinforcing that you’ll “be right back” and also strengthening their “alone endurance” is key for minimizing separation anxiety for a 21 month old.

Expert tip: Make leaving their room at bedtime fun! Try peek-a-boo with the door or make a fun “goodbye ritual” that makes them giggle, whether it be a silly song or book before you leave.

Smart Sleep Coach has a library of content written by sleep experts and pediatricians to help guide you through sleep at 21 months old.

Motor Skills Milestones for 21 Month Old

At 21 months old, children typically continue to develop their motor skills. Here are five 21 month old motor skills milestones you may continue to see:

  1. Walking and running: Most 21 month olds have mastered walking and are becoming more and more confident in their stride. They may also start running, albeit unsteadily, as they gain better control over their leg muscles. Keep in mind, even if they've been walking for some time, it’s still normal to crawl. It can be a fun way to explore, especially things that are lower to the ground.
  1. Climbing and crawling: Toddlers around this age typically love climbing on furniture or small structures, showing us how their balance and coordination is improving by the minute. Keep an eye on them—despite their confidence, they still may be wobbly.
  1. Fine motor skills: 21 month olds are constantly refining their fine motor skills, helping them to stack blocks, turn pages, and zip zippers. They may also show an interest in scribbling with crayons.
  1. Ball play:  Many toddlers at this age start to throw and kick balls, although their aim and coordination are still developing. These activities help improve hand-eye coordination and balance.
  1. Eating: Toddlers often like to feed themselves using utensils like spoons and forks, although it can be a messy process. This development of self-feeding skills enhances their hand-eye coordination and independence during mealtime.

It's important to remember that children develop at their own pace, and there can be some variation in the acquisition of these motor skills. If you have concerns about your child's motor development, consult with a pediatrician.

Communication Skills Milestones for 21 Month Old

By the age of 21 months, most toddlers have made significant strides in their communication skills. Gone are the days of seemingly meaningless babbling—your 21 month old is likely making their wants and needs very clear with their simple sentences, gestures, and the many words they now know.

Here is a list of communication milestones you may see your 21 month old reach:

  • Expanding vocabulary: Many 21 month olds may have a vocabulary of around 50-100 words that’s growing by the day. These words may include common nouns (such as "dog" or "ball"), action words (such as "eat" or "run"), and a bunch of descriptive words (like "big" or "happy"). Keep introducing new words to them every day—imitation is big at this age and the more you talk to them, the more they’ll learn.
  • Stringing together sentences: Around 21 months old is when toddlers often start to string together simple sentences. These sentences will typically be related to their basic needs or desires, such as "more juice" or "mommy help."
  • Pointing and making gestures: Pointing, nodding, and shaking heads is a common way for a 21 month old to communicate their needs or preferences. They might point at objects they want or gesture for you to come with them. Maybe they’ll even grab your hand and show you exactly!
  • Following simple directions: A common 21 month old developmental milestone is being able to follow simple, one-step directions, such as "give me the ball" or "clap your hands”.
  • Evolving social skills: Your 21 month old may becoming increasingly social and starting to engage in simple conversations, even if they don't always use complete (or understandable) sentences. They enjoy interacting with others and may engage in pretend play or role-play with toys. At this age they are starting to display empathy by pausing or looking sad if they see someone crying.
  • Becoming a little possessive: “Mine” is a common word around 21 months old, but don’t worry—this is very normal and will go away with time. Whether you are holding someone else's baby or another child is playing with a cool looking toy, don’t be shocked if they give a little attitude.

If you have concerns about your 21 month old not reaching their communication milestones, communication, speak with your pediatrician.

21 Month Old Mealtime Ideas

21 month olds are still picky—it’ll take some time to grow out of that. With newfound independence and opinions, eating (or not eating) is just one way your 21 month old exerts control. Here are some mealtime tips to get through the picky eating stage of toddlerhood.

  • Get creative: Make their plates intro art—use broccoli as trees and potatoes as a bed of snow. They may more into trying what's on their plate if it feels fun or special!
  • Try sauces: One way to introduce new tastes without overwhelming your 21 month old is with sauces. Dipping also makes mealtime more exciting! Hummus, dressings, or yogurt can all make a seemingly boring food item seem yummier.
  • Head to the market: Go grocery shopping with your 21 month old and have them choose some of the goods. Letting them select a new vegetable to try is one way to involve them in meal planning while also introducing them to a new food and sensory experience!
  • Jazz up their favorites: Identify a “safe” food and try and make it with a new ingredient. Whether it’s adding a vegetable into their pasta or putting fruit in their cereal, they may find out they like something they previously rejected.

Here are some healthy meal ideas to try out!

21 Month Old Milestones Checklist

Developmental milestones for a 21 month old may vary, but they often include a lot of movement, chatting, and feelings. Here's a general checklist of what you can typically expect. Remember that children develop at their own pace. Speak with your pediatrician if you’re concerned about anything related to your 21 month old’s developmental milestones.

  • Movement: From walking to running to climbing to jumping, your little one is likely on the move big time.
  • Playing: Stacking blocks and pretend play is big at this age. You may also see your 21 month old trying to turn the pages of books. Keep in mind that parallel play is normal for 21 month olds.
  • Imagination: Taking care of their dolls or pretend cooking are just some of the ways a 21 month old uses their imagination. Their minds are running wild—don’t be alarmed if they start waking up at night from their dreams. Talking it out with them and explain how it wasn’t real and they are safe may help them cope.
  • FOMO: With your 21 month old’s understanding of logic, they may not want you to leave them (whether it be at bedtime or with a sitter) because they know you’re somewhere doing something else. Keep reinforcing the concept of “being right back” by playing games such as hide and seek.
  • Chatting: 21 month olds often speak in two word sentences related to their basic wants or needs. Hearing their little voices communicate (or boss you around) is as cute as it is mind boggling!
  • Imitating: These little 21 month old sponges are always looking and listening. Careful of using certain words around them—even if you don’t know what they mean, they still will be used.
  • Tantrums: It’s frustrating not being understood 100% of the time! 21 month olds are also still developing emotionally—understanding big feelings take time.

Please remember: 21 month old developmental milestones can vary from one child to another. If you have concerns about your child's development or if you notice significant delays in any of these areas, consult with a pediatrician. Regular check-ups with your healthcare provider are a good opportunity to discuss your child's progress.

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FAQs:

Developmental milestones for a 21 month old may vary, but they often include a lot of movement, chatting, and feelings.

Many 21 month olds may have a vocabulary of around 50-100 words that’s growing by the day! These words may include common nouns (such as "dog" or "ball"), action words (such as "eat" or "run"), and a growing number of descriptive words (like "big" or "happy").

Many 21 month olds may have a vocabulary of around 50-100 words that’s growing by the day!

At this age, your child is a whirlwind of energy and curiosity, running around and exploring the world like they’re seeing everything for the first time—which often, they are! Their language skills are also rapidly developing, and they're eager to communicate, even if it's through a combination of words, sounds, and gestures. Their imagination is also starting to run wild, making playtime even more exciting.

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How We Wrote This Article

The information in this article is based on the expert advice found in trusted medical and government sources, such as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.

Sources

CDC, “How Much Sleep Do I need?”

American Academy of Pediatrics, “Caring for Your Baby and Young Child: Birth to Age 5”

American Academy of Pediatrics, “The Wonder Years”

American Academy of Pediatrics, “Media and Young Minds”

Journal of Clinical Sleep Medicine, “Toddler Bedtime Routines and Associations With Nighttime Sleep Duration and Maternal and Household Factors”

Behavioral Sleep Medicine, “The Family Context of Toddler Sleep: Routines, Sleep Environment, and Emotional Security Induction in the Hour before Bedtime”

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