This book describes ArTA, an evidence-based method for art therapy observation and assessment. This novel method argues the art-making process and art product are related to aspects of mental health. The results of the author’s own research show that observed patterns in material interaction, material experience, and the specific combinations of formal elements of the art product reveal the client’s balance between thinking and feeling, and adaptability. Divided into four sections, the book illustrates this research, theory, and application of the ArTA method using examples and case histories with clear frameworks that give guidance in art therapy observation and assessment. It provides direction for formulating treatment goals and drawing up appropriate treatment interventions. Intended for art therapy students and practicing art therapists, this methodology will challenge readers to rethink the relationship between a client’s interaction with art materials and their mental health.