What’s the Difference In Orton-Gillingham, Science of Reading, LETRS, and IMSE?

Hint: Not as much as you think.

While teaching Orton-Gillingham (OG), I often come across other approaches like the Science of Reading, LETRS, and IMSE. At first, I wondered: Are these all different programs? Do I need to learn them all? But once I began digging into the details, I realized something important—they’re all speaking the same language.

Whether you’re a tutor, teacher, or homeschool parent, it helps to know how these approaches fit together—and how they’re actually more connected than they seem.

Let’s unpack it together.

The Common Thread: Structured Literacy

Whether you’re talking about OG, the Science of Reading (SoR), LETRS, or IMSE, they all fall under the umbrella called Structured Literacy. That just means reading is taught in a planned, clear, and layered way — like in the OGforALL Scope and Sequence. There’s no guessing. Each lesson builds on the one before it, with constant review and reinforcement.

If you’ve ever taught a child to tap out sounds, trace letters while saying sounds aloud, or decode syllables in a specific order, you’re using Structured Literacy.

Where Did It All Begin?

The roots of these methods go back to Orton-Gillingham, which was developed in the 1930s by neuropsychiatrist Dr. Samuel Orton and educator Anna Gillingham. Their approach was designed specifically for struggling readers, particularly those with dyslexia. It emphasized multi-sensory instruction—using sight, sound, movement, and touch to help kids make lasting connections with language.

In short, OG was the original.

Since then, others have taken core OG ideas and expanded on them. Some, like IMSE (Institute for Multi-Sensory Education), offer OG-based training and materials. Others, like LETRS, focus on helping teachers understand the research behind reading and how to apply it in the classroom.

So, What’s the Difference?

The difference is mostly in the packaging and purpose:

Orton-Gillingham

OG is an instructional approach rooted in research and built on a scope and sequence. While it was originally created for students with dyslexia, today more educators recognize it as an effective approach for everyone. When students learn this way, they gain a strong understanding of how the English language works—sound by sound, rule by rule.

Science of Reading (SoR)

SoR is a body of research behind how the brain learns to read. It breaks reading into key components that must be taught explicitly and in a specific order:

• Phonemic awareness (hearing and manipulating sounds)
• Phonics (matching sounds to letters)
• Fluency (reading with speed and accuracy)
• Vocabulary
• Comprehension

SoR tells us what should be taught and why. Educators and companies then build programs that follow this research.

That’s why you’ll hear about:

• LETRS, a teacher training course grounded in SoR principles
• Heggerty, a program focused on phonemic awareness
• Fundations, UFLI, and IMSE, which provide structured phonics instruction

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LETRS (Language Essentials for Teachers of Reading and Spelling)

LETRS is a professional development course that trains educators in the science of how students learn to read and how to apply that science in the classroom. It’s focused more on teacher knowledge than student materials.

IMSE (Institute for Multi-Sensory Education)

IMSE is a company that provides OG-based training and materials. While it’s not the original Orton-Gillingham method, it builds on OG principles and blends them with Science of Reading research.

Bottom Line

All of these approaches may use different terminology or tools, but they share the same foundation— one that began with Orton-Gillingham.

Why Does It Matter?

If you’re a tutor, teacher, or homeschool parent, it can be overwhelming to hear all these different names. But rest assured: if you’re using a multi-sensory, structured, and cumulative approach, you’re doing it right.

These aren’t competing ideas. They’re companion strategies that support the same mission. They are all seeing kids become capable readers (and spellers too!).

Next Steps

If you’re ready to go deeper with the Orton-Gillingham approach and build a solid foundation for structured literacy instruction, there’s a resource just for you.

The Orton-Gillingham Blueprint: Essential Strategies and Instruction is a course for tutors, teachers, and parents who want to confidently teach reading using the OG approach.

Click here to explore the course.

Start Teaching with Ready-To-Go Lessons!

Read & Spell Foundations | Consonants and Short Vowels (Structured lessons, no special training required)
Fast Track Bundle | Scope & Sequence Workbooks 1 &2 + Drill Cards

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Orton-Gillingham, the Science of Reading, LETRS, and IMSE may sound different, but they’re all rooted in the same principles of Structured Literacy. Using a systematic, explicit, and cumulative approach, OG helps students master the building blocks of reading and spelling. Whether you’re using OG alone or alongside SOR-aligned programs, this method continues to be a trusted foundation for literacy instruction.