Bilingual Toddler Milestones: 12-24 Months

Quick answer: Between 12 and 24 months, toddlers typically move from a handful of single words to a rapidly growing vocabulary and, by the end of the window, simple two-word combinations — and for bilingual toddlers, this growth is usually split across two languages rather than concentrated in one, which is why total vocabulary (not per-language vocabulary) is the more meaningful measure.

The general shape of the second year

The second year is when spoken language usually goes from a handful of scattered words to something recognizably conversational. This period follows a broadly consistent pattern across children — a slow start, a marked acceleration in vocabulary sometime in the middle of the year, and the beginnings of word combinations toward the end of it. Bilingual toddlers follow this same general arc; what differs is how the vocabulary is distributed.

12-15 months: a small, growing set of single words

Most toddlers have a modest handful of consistent words at this stage — often people, common objects, and a few actions or requests. Comprehension is far ahead of speech: toddlers this age typically understand many more words than they can say, including simple instructions and the names of familiar objects and people. In a bilingual household, a toddler's spoken words at this stage might come from either language depending on which word they've heard most in a given context — it's common for a toddler to have some words only in Chinese and others only in English, rather than a matched set in both.

15-18 months: the vocabulary curve starts to bend upward

For many toddlers, this is when word acquisition visibly speeds up — new words are picked up more quickly, and there's often a noticeable jump in how much a toddler is attempting to say, even if pronunciation is still rough. For a bilingual toddler, this acceleration applies to their overall vocabulary; the split between languages at this stage often continues to reflect which language dominates specific contexts (say, mealtime words in Chinese if that's the language used at meals, or animal names in English if that's the language of a favorite book).

18-24 months: two-word combinations begin

Toward the latter part of this window, many toddlers start combining two words into simple phrases — "more milk," "mama go," "no nap." This marks an important shift from single-word requests toward actual sentence-building. Bilingual toddlers reach this stage on the same general timeline; their two-word combinations may occur within a single language, or occasionally mix both ("要 more" or "want 抱抱"), which — as covered in more depth in our piece on code-switching — is a completely normal feature of bilingual speech, not a sign of confusion.

Total vocabulary vs. per-language vocabulary

This is one of the most important concepts for parents tracking a bilingual toddler's progress. If you count only the Chinese words or only the English words a toddler produces, the number may look smaller than what a monolingual toddler the same age is saying. But bilingual toddlers are building two vocabularies simultaneously, and the more meaningful comparison is total vocabulary across both languages — words a toddler can say in either language, without double-counting near-equivalents. Measured this way, total vocabulary in bilingual toddlers is generally comparable to monolingual toddlers' vocabulary size. A smaller per-language count is an expected feature of splitting input across two systems, not evidence of a problem.

The "silent period"

Some bilingual toddlers go through a stretch — sometimes weeks, sometimes longer — where they talk noticeably less than before, or lean much more heavily on one language than the other. This often coincides with a change in their exposure environment, such as starting daycare or preschool where a new language (often the majority community language) suddenly dominates their day. During this period, a toddler may be quietly absorbing and reorganizing rather than actively producing much speech in one or both languages. This pattern is widely recognized as a normal, usually temporary phase in bilingual development, and most toddlers resume more active speech, often with a noticeable jump in the newly-emphasized language, once they've adjusted.

What this means day to day

• Don't compare your bilingual toddler's single-language word count directly to a monolingual chart without accounting for the split — total vocabulary is the fairer comparison.
• A quieter stretch, especially around a transition like starting daycare, is common and usually resolves on its own with continued exposure.
• Keep providing consistent input in both languages through this period, even if output (speech) temporarily favors one — comprehension in the quieter language is very likely still building in the background.

Continue the timeline

For what came before, see Bilingual Baby Milestones: 0-12 Months. If your toddler seems to understand far more than they say, When Do Babies Start Understanding Language? explains why that gap is expected — or find staged next steps on the Growth Roadmap.