RPM vs S2C vs Spellers Method: What is the Difference?

The Question Every Family Asks

When families first discover the world of spelling-based communication, they quickly encounter three names: RPM, S2C, and Spellers Method. Each has passionate advocates. Each has certified providers. And to an outside observer, they can look remarkably similar — a nonspeaking person pointing to letters on a board.

So what's the difference? And how do you know which one to pursue for your child?

This guide breaks it down clearly, without bias. All three methods share the same core belief: that nonspeaking individuals are intelligent and capable of communicating. The differences are mostly in approach, training, and philosophy.

What They All Have in Common

Before getting into differences, it's worth naming what RPM, S2C, and Spellers Method all share:

• They all use letterboards. A flat surface with the alphabet printed on it. The learner points to letters to spell words.
• They all presume competence. Each method is built on the belief that nonspeaking individuals understand far more than they can show through conventional means.
• They all work toward independence. The goal in each approach is to reduce support over time and build toward fully independent communication.
• They all have certified training pathways. Each method has an organization that trains and certifies practitioners.

The families who have found success with each method describe strikingly similar experiences: a child who was assumed to have little to say, a first session, a first spelled word, and a life that was never the same again.

RPM (Rapid Prompting Method)

Developed by: Soma Mukhopadhyay

Certifying organization: HALO (Helping Autism through Learning and Outreach)

Website: halo-soma.org

RPM is the oldest of the three methods covered here. Soma Mukhopadhyay developed it while working with her own son Tito, who is nonspeaking and autistic — and who went on to become a published poet and author.

### What makes RPM distinct:

Academic content is central. RPM sessions are built around genuinely stimulating academic material — science, history, literature, math. The idea is that engaging the mind through interesting content naturally draws out communication. This is not therapy in the traditional sense; it looks more like a tutoring session.

The "rapid" matters. The pacing in RPM is intentionally fast. Soma observed that a quick pace helps keep the learner's attention and motor system engaged, reducing the "noise" of self-stimulatory behavior and bringing focus to the letterboard.

Certification levels. HALO certifies providers at four levels (1-4), with Level 4 being the most experienced. Many families seek out Level 3 or 4 providers for their depth of experience.

Best fit: Families who want a structured, academic framework and are drawn to the history of RPM and Soma's body of work.

S2C (Spelling to Communicate)

Developed by: Elizabeth Vosseller, SLP

Certifying organization: I-ASC (International Association for Spelling as Communication)

Website: i-asc.org

S2C was developed by Elizabeth Vosseller, a speech-language pathologist who approached letterboard communication through the lens of motor science. S2C places particular emphasis on the motor planning challenges that many nonspeaking autistic individuals face.

### What makes S2C distinct:

Motor-first philosophy. S2C frames communication challenges primarily as motor challenges — the body not reliably doing what the mind intends. Before spelling words, S2C works to build a reliable motor pathway for pointing. Sessions progress through defined stages: open/close, point, letterboard, keyboard.

Gradual, systematic progression. The stage-based structure of S2C gives families and practitioners a clear framework for understanding where a learner is and what comes next. This systematic approach appeals to many families and educators who want clear milestones.

Strong practitioner community. I-ASC has built a robust global community of certified practitioners, with active training programs and ongoing professional development.

Best fit: Families who want a structured, motor-informed approach with clear progression stages and a large community of certified practitioners to choose from.

Spellers Method

Developed by: Dana Johnson

Certifying organization: Spellers (spellers.com)

Website: spellers.com

Spellers Method is the newest of the three and integrates letterboard communication with a broader therapeutic framework that includes occupational therapy, developmental optometry, and assistive technology.

### What makes Spellers Method distinct:

Holistic integration. Spellers Method explicitly incorporates OT, vision therapy, and AT alongside letterboard work. The approach recognizes that communication challenges often coexist with sensory, visual, and regulatory challenges — and addresses them together.

Emphasis on the whole person. Beyond communication, Spellers Method focuses on quality of life, self-regulation, and building a full support system around the individual. It is not just about spelling; it is about thriving.

Growing provider network. While currently smaller than the RPM and S2C provider communities, the Spellers network is growing and has a dedicated certifying body.

Best fit: Families looking for an integrated approach that addresses sensory, motor, and communication needs together, especially where OT is already part of the picture.

So How Do You Choose?

Honestly? For most families, the best method is the one where you can find a qualified, experienced provider who connects well with your child.

The philosophical differences between RPM, S2C, and Spellers Method are real — but they are smaller than the difference between a great provider and a mediocre one. A skilled Level 4 RPM practitioner and a skilled I-ASC Trainer are both going to give your child a far better experience than a Level 1 provider in any method who is still finding their footing.

That said, here are a few practical questions to help guide your thinking:

Is there a qualified provider near me? Start with geography. Use our directory to see what certified providers exist in your state and whether they offer virtual sessions.

Does my child already have an OT relationship? If OT is central to your child's support, Spellers Method's integrated approach might be a natural fit.

Does the academic framing appeal to me? If you're drawn to the idea of treating your child as an intellectual peer from day one, RPM's academic-first approach may resonate.

Is systematic progression important to me? If you want clear stages and milestones, S2C's structured framework provides that.

What does the community look like near me? Local family groups, support networks, and provider communities vary by region. Sometimes the method with the strongest local community is the right choice simply because of the support network it offers.

A Final Word

Do not let the decision about which method to pursue become a barrier to getting started. All three methods have changed lives. All three have families who are deeply grateful they found them. The common thread is not the method — it is the decision to presume competence and find a way to let your child speak.

Use our directory to find a certified provider in any of these methods. Reach out to a few. Ask questions. And take the first step.

[Find a certified provider near you →](/find-provider)