It’s a common assumption that learning similar languages makes for an easier path to fluency. For example, a Spanish speaker learning Portuguese should have less trouble than an English speaker pursuing Japanese. Is this really true? In this post, I’ll share my experience learning similar languages — and the unique advantages and challenges that come with it.

The Advantage of Familiarity

When we learn a new language, our brain naturally tries to relate unfamiliar sounds and words to something we already know. This makes learning similar languages a clear advantage. As we immerse ourselves in the target language, we can latch onto similarities and experiment with the language with more confidence.

For instance, if you already know Spanish, picking up Italian or Portuguese is much easier. There’s a massive overlap in vocabulary, structure, and even rhythm. The same goes for Russian and Ukrainian, or even Standard Arabic and Levantine Arabic.

From a vocabulary perspective, the benefit is clear. If 60–70% of the words are recognizable or share roots with a language you already speak, you’ll acquire new words faster. In other words, there may just be less words to acquire. This is advantageous, as developing a large vocabulary is one of the biggest hurdles in language learning.

My Experience with Related Languages

When learning French, I was often able to draw on English to accelerate my learning. Roughly half the vocabulary in French is recognizable to English speakers. That shared linguistic ancestry gives you a head start.

Similarly, after learning Spanish, I found that I could understand a lot of Portuguese — at least passively — right away. That made learning similar languages both satisfying and efficient, especially in the early stages.

The Hidden Challenges of Learning Similar Languages

However, learning similar languages is not all smooth sailing. One of the biggest challenges I’ve encountered is interference — when elements from one language creep into another. When I speak Portuguese, for example, I often get accused of speaking Portuñol — a Spanish-Portuguese hybrid.

Why is Spanish such a visible influence in my Portuguese? Because it’s hard to suppress habits and patterns from a similar language that you already know. Your brain not only defaults to familiar words and patterns for communication, but also suppresses what is irrelevant. This is harder to do when the languages have so many similarities.

I’ve seen the same issue when navigating other language pairs: Czech and Russian, French and Italian, even Levantine Arabic after learning Modern Standard Arabic. The comprehension is strong, but producing the language without mixing elements takes more effort.

Romanian: An Interesting Case Study

My experience with Romanian differed from when I learned other Romance languages. While 70% of its vocabulary is rooted in the Romance family, the structure is quite different. That difference actually made it easier for me to keep the language distinct in my mind. Less overlap with Spanish, French, etc. meant fewer chances to confuse things.

Final Thoughts: Comprehension Comes First

At the end of the day, I always return to a core principle: comprehension is the foundation of all language learning. Even if you occasionally mix similar languages, as long as you understand well and stay consistent, your ability to separate and use the languages more precisely will improve.

In summary, is learning similar languages an advantage? Absolutely — especially when it comes to vocabulary acquisition and comprehension. But it also requires a level of awareness and patience to manage interference and avoid fossilizing bad habits.

I’ve learned that, no matter how close two languages are, each one deserves its own space and respect.