Book excerpt: How does mindfulness work? Thousands of therapists utilize mindfulness-based treatments and have witnessed firsthand the effectiveness of these approaches on clients suffering from anxiety, depression, and other common mental health issues. But for many clinicians, the psychological processes and brain functions that explain these changes remain a mystery, and effective methodologies for measuring each client's progress are elusive. In Assessing Mindfulness and Acceptance Processes in Clients, Ruth Baer presents a collection of articles by some of the most respected mindfulness researchers and therapists practicing today. Each contribution assesses the variables that represent potential processes of change, such as mindfulness, acceptance, self-compassion, spirituality, and focus on values, and determines the importance of each of these processes to enhanced psychological functioning and quality of life. Clinicians learn to accurately measure each process in individual clients, an invaluable skill for any practicing therapist. A seminal contribution to the existing professional literature on mindfulness-based treatments, this book is also an essential resource for any mental health professional seeking to illuminate the processes at work behind any mindfulness and acceptance-based therapy. The Mindfulness and Acceptance Practica Series As mindfulness and acceptance-based therapies gain momentum in the field of mental health, it is increasingly important for professionals to understand the full range of their applications. To keep up with the growing demand for authoritative resources on these treatments, The Mindfulness and Acceptance Practica Series was created. These edited books cover a range of evidence-based treatments, such as acceptance and commitment therapy (ACT), cognitive behavioral therapy (CBT), compassion-focused therapy (CFT), dialectical behavioral therapy (DBT), and mindfulness-based stress reduction (MBSR) therapy. Incorporating new research in the field of psychology, these books are powerful tools for mental health clinicians, researchers, advanced students, and anyone interested in the growth of mindfulness and acceptance strategies.