Welcome to the Diploma in Acceptance & Commitment Therapy

Welcome — and congratulations on enrolling. Acceptance and Commitment Therapy is one of the most widely used third-wave cognitive behavioural approaches, with strong evidence across anxiety, depression, and chronic pain. Over the next six units, you’ll build a genuine working understanding of ACT — not just the theory, but how to bring it into real client work alongside your existing CBT or DBT practice.

I’m Dr. John Crimmins, and I’ll be your tutor throughout this diploma. I bring 25 years of clinical experience across CBT, addiction treatment, and crisis and trauma work — and I’ve built this course to be genuinely practical, not just academic. You’ll come away with a genuine working knowledge of ACT’s core techniques, ready to bring into your existing clinical practice.

How This Course Works

This diploma is fully self-paced — study in your own time, at your own speed. We’d recommend working through the six units in order, since each builds directly on the last.

What You’ll Learn

Unit 1 — Foundations of ACT: The Third Wave & Psychological Flexibility

Where ACT sits within third-wave CBT, the psychological flexibility model, and why working with difficult thoughts and feelings works better than fighting them.

Unit 2 — Acceptance & Cognitive Defusion

Exploring how ACT approaches unwanted thoughts and feelings, and the core defusion techniques used across the model.

Unit 3 — Present-Moment Awareness & Self-as-Context

Mindfulness within ACT, and how the model understands a stable sense of self beneath thoughts and stories.

Your first assignment follows this unit — see Assessment below.

Unit 4 — Values & Committed Action

How ACT approaches values clarification, and the process of turning values into sustained, workable behaviour change.

Unit 5 — ACT Case Formulation & Applying ACT Across Presentations

How an ACT case formulation is built, and how the model addresses anxiety, depression, and chronic pain presentations.

Unit 6 — The Therapeutic Relationship in ACT & Integrating ACT with CBT/DBT Practice

How the therapeutic relationship itself functions as an ACT process, and how ACT can sit alongside your existing CBT and DBT knowledge.

By the end of the diploma, you’ll be able to explain ACT’s theoretical foundations, understand how its six core processes work together in session, explore acceptance and defusion techniques, understand how to support values clarification and committed action, recognise how an ACT case formulation is built across common presentations, and consider how ACT can complement your wider clinical practice.

Assessment

Assessment has two parts:

Written assignment — a 1,500-word essay, submitted after Unit 3
Final quiz — completed after Unit 6, to close out the diploma

Once you’ve successfully completed both, your official Diploma in Acceptance & Commitment Therapy will be emailed to you separately, along with a letter confirming your successful achievement.

Getting Started

Simply click into Unit 1 below to begin. If you have any questions as you work through the material, you’re welcome to reach out — I read and respond to every message personally.

Good luck, and welcome aboard.
— Dr. John Crimmins