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What is Second Language Acquisition (and why does it matter)?


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Bonjour! Aloha! Welcome to Adventures in Language. There is so much to say about the science behind language learning, but in this article, we’re going to start with the basics. We’re focusing on two big questions: What is Second Language Acquisition and why does it matter?

Languages are incredibly complex. Take a minute to think about this: What are you learning when you learn a new language? 

  • Thousands of words
  • Rules for how to put those words together
  • A new sound system
  • Idioms and expressions
  • Information about when it’s appropriate to say what
  • Cultural competence

And much, much more!

It’s a lot! And we know that people all over the world learn languages every day for many different reasons, in many different contexts…and with a very wide range of success. We probably all have that one friend who seems to pick up new languages effortlessly, yet many of us struggle to get past basic vocabulary and greetings. To understand more about how people learn languages, we can turn to Second Language Acquisition. And that brings us to our first question...

What is Second Language Acquisition? 

Let’s start with the short answer. Linguistics is the scientific study of language. Second Language Acquisition (or SLA, if you want to sound like you’re in the know) is the subfield of linguistics that focuses on the learning and teaching of second languages.

Now, the word  ‘second’ in Second Language Acquisition can be a little misleading. Because actually, SLA involves the study of any language learned after your first language (or first languages - many people have multiple first languages!), so that could be your second language, but it could also be your third, fourth, fifth… fifteenth... and so on! baby-focus-photo-blog

First language learning, though, does not fall under the umbrella of SLA. Child language acquisition, or first language acquisition, is a distinct field of study at the intersection of linguistics and developmental psychology. Of course, there’s a lot of overlap there! The similarities and differences between first and second language acquisition warrant an entire blog post. But for now, let’s stick to SLA. 

Second Language Acquisition involves the study of any additional languages. So that could be your 2nd language, but it could also be your 3rd, 4th, 5th… and so on!


A Brief History of Second Language Acquisition

Serious efforts to study second language learning emerged in the mid-1900s, when researchers were starting to look at how insights from psychology, theoretical linguistics, and first language acquisition could inform our understanding of how adults learn additional languages, and how this could apply to language teaching

By the 1980s, SLA was really being established as a field of study in its own right. This is when early and influential theories about second language learning started to take hold. These theories considered questions like:

  • Are humans born with knowledge of grammatical rules, and can they access these rules when learning a second language?
  • How does your first language help - or hurt - when you learn a second language?
  • What makes face-to-face conversation so valuable for language learning?
  • How is it possible for someone to know grammar rules, but still make mistakes when they speak or write in a second language? 


SLA is an extremely interdisciplinary field that has connections to many different areas of study.

These early theories paved the way for an explosion of research that has flourished to this day, intersecting with a wide range of scientific fields, including sociology, anthropology, cognitive science, neuroscience, and education.

Early SLA theories focused on topics like how some learners know grammar rules but still make mistakes when speaking.

Today, there are many academic journals that specifically focus on SLA, and a Google Scholar search for academic publications on “second language acquisition” returns nearly 4 million results! SLA even has its own subfields. Generally, these are divided into two main strands - an applied strand that focuses on how to make language learning and teaching more effective, and a pure research strand that focuses on understanding how language learning works, or characterizing the human ability to learn new languages.


A Google Scholar search for “second language acquisition” returns nearly 4 million academic publications on the topic.


Why does it matter?

Now that you know more about what SLA is and where it came from, it’s time to explore the second part — why it matters. As it turns out, understanding second language learning has many real-world implications. Let’s look at just 5 main examples:



  1. This first one may sound obvious, but SLA is important for education

Teaching programs, textbooks, curriculum designs, and even the activities in your language classrooms are often informed by SLA research. Beyond the classroom, people learn languages at all ages in a variety of contexts for a number of different reasons, and they all come at it with different strengths and weaknesses - SLA research seeks to understand how all of these different factors, and more, influence language learning.


  1. SLA is important for public policy

In many countries, immigrants make up a large number of second language learners - SLA research can inform policies about how and when to educate these newcomers in the local language while maintaining their home languages.


  1. SLA is important for national security and diplomacy

The Department of Defense is actually one of the biggest funders of SLA research. They need to identify talented language learners who can quickly learn to communicate with the diplomats and locals all over the world… oh, and they’re probably training spies.



  1. SLA is important for the economy

More and more jobs are requiring proficiency in another language, and in many fields, learning a second language can make you a more competitive candidate.




  1. There are so many real-world applications of SLA - more than we can touch on in one video. But perhaps the most important application of SLA is its role in cross-cultural understanding. SLA research shows that learning new languages makes us more open to other cultures and broadens our worldview.

The Future of Second Language Acquisition

SLA research attempts to answer a wide variety of questions, including:

  • Does age affect language learning?
  • Are some languages harder to learn than others?
  • Why is it so hard to lose your foreign accent?
  • How does speaking a second language affect your identity?
  • How does the brain process second languages?
  • Does learning a second language improve your tolerance of other cultures?
  • And many more…

SLA has implications for:

  • Education
  • Public policy
  • National security and diplomacy
  • the Economy
  • Cross-cultural understanding 

But there is still a lot we don’t know about language learning, and SLA researchers are hard at work trying to give us some answers!

To recap, here are 3 main takeaways from this article:

  1. Second Language Acquisition (aka SLA) is a subfield of linguistics that focuses on the learning and teaching of second languages. 
  2. Within SLA, a “second” language refers to any language learned after your first language, beyond the first few years of life. 
  3. SLA is relevant to many areas of our everyday lives, including, but not limited to education, public policy, national security and diplomacy, the economy, and cross-cultural understanding. 

If you found this article helpful, please let us know. And as always, if you have an idea of a language article or resource you’d like to see - tell us in the comments! 


Thanks for reading!

If you liked this article, let us know! Want more engaging language content like this? Subscribe to our YouTube channel and podcast feed, and follow us on Instagram @MangoLanguages! Or visit us at Mangolanguages.com!

Fill out the form below for some fun and free materials on Second Language Acquisition. Aloha! Au revoir et à bientôt ! We look forward to seeing you back here for our next article. To embark on your next language learning adventure, visit us at Mangolanguages.com!

Wondering what languages were used in today’s article?

Bonjour (bo(n)joor) and Au Revoir et à bientôt (o reuvwar ay ah beea(n)to)  mean “hello” and “goodbye and see you soon” in French, a Romance language that originated in France and is now spoken all over the world. Aloha (ahLOHhah) means both “hello” and “goodbye” in Hawaiian, a polynesian language that is one of the two official languages of Hawaii.

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Kaitlyn Tagarelli

Kaitlyn is a Linguist and the Head of Research at Mango Languages. She holds a Ph.D. in Linguistics from Georgetown University, specializing in how the mind and brain learn languages. Aside from geeking out about all things neuroscience and linguistics, she loves hanging out with her family at their Connecticut home, trying to convince them to speak French with her.

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