Book excerpt: Among mental health researchers, there is a consensus that empirically supported treatments (ESTs) have favorable outcomes and that the outcomes are typically better than other approaches. The majority of these are available as therapist manuals, brief books, or other extended volumes. However, among mental health service providers, there is often a view that these manuals and books can be formulaic and rigid, and likely insensitive to individual patient needs or presentations. With these conflicting perspectives in place, there is a need for accurate communication and reconciliation. Flexibility within Fidelity identifies how effective ESTs can be implemented with both integrity and flexibility. The book is comprised of chapters focusing on specific ESTs for identified problem areas amongst adults and children/adolescents, including anxiety disorders, PTSD, pain management, and depression among others. Chapter authors focus on the specific treatment components that are required to maintain fidelity and the features of the EST which can be applied with flexibility, promoting a personalized implementation. Written in an accessible style featuring in-depth clinical discussions, this book will equip mental health practitioners with the tools to implement ESTs across client presentations.