CISO: Evolution of a Vocation comprises three levels. The first level shares the author’s personal journey, beginning as a homeless college dropout and culminating in over thirty years of service as a CISO and in CISO‑equivalent roles at some of America’s most iconic companies and organizations. Drawing on experience and discipline gained from military contracting work, the author maintained a letter log system to manage the commitments and document the issues he faced. He also kept digital copies of over 1,000 memorandums issued during his later CISO roles. Through excerpts from selected memos, readers gain an unprecedented view into the cybersecurity challenges he confronted as CISO. Each chapter includes “Lessons Learned,” providing readers with the benefits of the author’s life lessons and cybersecurity experiences. Where warranted, the author recognizes his “All Star” team members whom he had the privilege of working with. In addition to his personal journey, this book explores the history of major technology advancements and significant security events occurring from 1971 to 2017. This provides valuable context for understanding how the landscape of cybersecurity has evolved over the decades. Building on these experiences, this book examines the evolution of the CISO role itself. Readers follow the progression from the role’s early inception to its current status as a true business leadership position. Each level makes this book accessible and engaging for both general readers and professionals.