10 Common ESL Mistakes in Thesis Writing (and How to Fix Them in 2025)

ByJenny Hill, PhD

Introduction

Writing your thesis is already overwhelming enough. But doing it in a second language? That’s a whole other level of stress.

You probably know your research like the back of your hand, but when it comes to putting it into academic English, it can feel like you’re constantly second-guessing every sentence.

Sound familiar?

You’re not alone. A lot of ESL grad students struggle with the same things—grammar rules that make no sense, awkward sentence structures, and this constant fear that your writing sounds “off.”

But here’s the truth: your ideas are valuable, and your language challenges shouldn’t hold them back. You just need to learn how to spot the most common mistakes and fix them the smart way.

So let’s walk through the ten most common ESL mistakes in thesis writing—and how to avoid them like a pro.

1. Misusing Articles (a, an, the)

If you’ve ever wondered whether to write “a theory,” “the theory,” or just “theory,” welcome to the club. Articles are one of the trickiest parts of English because they don’t always exist in other languages.

You might say things like “the nature is beautiful” or “an information is missing,” and while it makes sense in your head, it’s just not how native English speakers phrase it.

What you can do:

  • Use “a” or “an” when introducing something new. Use “the” when referring to something already mentioned.
  • Don’t use articles before uncountable nouns like “information,” “research,” or “advice.”
  • Read other academic papers and highlight article usage—it helps way more than just memorizing grammar rules.

2. Wordiness and Repetition

There’s this weird pressure to sound “academic” in your writing, right? So you add words. A lot of them. But more isn’t always better. Over-explaining can make your writing feel bloated and unclear.

For example, instead of saying “Due to the fact that…,” just say “Because.” Simpler is stronger.

Quick fix:

  • Say what you mean once, then stop. Repetition doesn’t make your point stronger.
  • Use Grammarly or Hemingway Editor to highlight wordy sentences.
  • Practice trimming your writing during revisions—cut 10% from each paragraph on your first thesis edit.

3. Incorrect Verb Tenses

Verb tenses are sneaky. You might start a paragraph in past tense and accidentally switch to present perfect halfway through. And in academic writing, that can really confuse your readers.

I’ve seen entire literature reviews flip between tenses like a tennis match—and guess what? It makes your argument harder to follow.

How to fix it:

  • Use past tense for completed research and present tense for facts or general truths.
  • Keep one consistent tense per paragraph unless you’re shifting timelines.
  • Make a “tense map” for each section of your thesis so you know what to stick with.

4. Sentence Structure and Run-ons

Have you ever written a sentence that just keeps going and going and then suddenly realize you’ve completely lost track of what you were even trying to say? Yeah, that’s probably a run-on sentence.

Or maybe you’ve written sentence fragments like “Because the theory failed.” (Wait, what happened because of the theory?)

What works better:

  • Read your sentences aloud. If you run out of breath, it’s probably too long.
  • Use punctuation marks—especially commas, colons, and semi-colons—to break ideas up.
  • Combine short, choppy ideas using connectors like “although,” “however,” or “moreover.”

5. Direct Translation from Your Native Language

This one’s personal for a lot of people. You think of a perfect phrase in your native language, then translate it directly to English. But what comes out sounds…off. Not wrong exactly, but awkward. Unnatural.

Academic English has its own rhythm, and direct translations usually mess with that flow.

Your best bet:

  • Write your first draft in simple English. Don’t worry about fancy words.
  • Then revise to match the tone of academic writing.
  • Use examples from published research in your field to model sentence structure.

6. Misuse of Academic Vocabulary

Let’s be honest—sometimes you throw in a big word just to sound smart. We all do it. But misusing academic vocabulary can make your writing confusing or even incorrect.

You might use a word like “significant” thinking it means “important,” when in research it actually means “statistically meaningful.”

Here’s what helps:

  • Keep a personal word bank of academic terms you fully understand.
  • Look up words in academic contexts, not just in the dictionary.
  • Avoid thesaurus traps—swapping words can mess up nuance if you’re not sure of the meaning.

7. Lack of Cohesion and Transition Words

If your paragraphs feel like puzzle pieces from different boxes, you probably need better transitions. Without cohesion, your thesis feels disjointed—even if each part is strong on its own.

I used to think “In addition” and “However” were enough. But real cohesion goes deeper than that.

Try this:

  • Use signposting language like “This chapter explores…” or “The next section will discuss…”
  • Link each paragraph to the one before it using transitional phrases.
  • Think of your writing like a story—each part should lead naturally to the next.

8. Inconsistent Referencing Style

You know what’s worse than fixing references? Getting a low grade because your citations were inconsistent. One moment it’s APA 7th, the next it’s some Frankenstein hybrid of MLA and whatever you last saw online.

As an ESL writer, formatting citations manually can get really frustrating, especially with different punctuation rules.

What to do:

  • Choose one citation style early and stick with it.
  • Use tools like Zotero, EndNote, or Mendeley to manage citations.
  • Triple-check in-text citations and bibliography entries during your final edit.

9. Overuse of Passive Voice

Passive voice isn’t evil—it actually has a place in academic writing. But when you overuse it, your thesis starts to feel vague and impersonal.

Instead of “It is believed that…” try “Researchers argue that…”

What helps:

  • Use active voice when you’re presenting your own analysis.
  • Use passive voice selectively—like when focusing on processes rather than people.
  • Practice rewriting your own sentences both ways to get a feel for what sounds clearer.

10. Difficulty Expressing Critical Thinking

One of the hardest things as an ESL writer is learning how to go beyond just reporting what others said. Critical thinking isn’t just about disagreeing—it’s about evaluating, comparing, and interpreting.

But expressing those ideas in English takes skill. And confidence.

Here’s how you grow that skill:

  • Use phrases like “This suggests that…” or “A possible explanation is…”
  • Ask yourself “So what?” after each paragraph. Push your thinking deeper.
  • Read model essays in your field and notice how they critique and synthesize ideas.

Conclusion

Writing a thesis in English when it’s not your first language is no small task. But you don’t need to be a native speaker to write a great thesis—you just need awareness, practice, and the right strategies.

Now that you know the most common ESL mistakes in thesis writing, you’re already ahead of the game. Don’t aim for perfection—aim for progress. Every revision, every rephrased sentence, every new transition word you master brings you one step closer to clarity and confidence.

So go back to that thesis draft with fresh eyes. Use what you’ve learned here. And if you need help? Don’t be afraid to ask for it. You’ve got this.