ISA Therapy: Volume 1 - Foundations of ISA Therapy presents the philosophical and clinical framework of an integrated, connection-first therapeutic model designed to support neurodivergent individuals across developmental stages. Grounded in research and informed by lived clinical practice, this foundational text outlines the core principles of ISA Therapy, including relational safety, individualized engagement, and interdisciplinary collaboration. The volume details the intentional integration of music, art, speech-language, occupational, and recreational therapies within a cohesive framework, emphasizing holistic brain-body engagement and ethical, adaptive care. Designed as a professional reference, this text establishes the origin framework of ISA Therapy for clinicians, educators, institutions, and interdisciplinary teams seeking a structured, neurodiversity-affirming approach to therapeutic practice.