Puerto Rico is a non-incorporated territory that belongs to the United States of America since the US military invasion of Puerto Rico in 1898. With these 108 years of colonization by the United States plus the 405 years of colonization by Spain, Puerto Rico is entitled to be called The World’s Oldest Colony in present times. This is a fact that is not well known to the U.S. population and surprisingly, not by many Puerto Ricans either. This book addresses this problem. What is different about this writing is that its presents a Puerto Rican psychiatrist’s view of this problem. After working for the past thirty three years as a practicing general Community Psychiatrist in Puerto Rico and in New Bedford, Massachusetts, I have collected very detailed observations about the personalities of my patients who are mostly Puerto Ricans. I have discovered a personality style unique to this population: The Colonized Personality. This book is addressed to the general educated population, both in Puerto Rico and in the United States of America, that have interest in Puerto Rican affairs. The book is divided into seven sections. 1. Preface. Here I define from where the idea of talking about the Puerto Rican personality originated. It also describes my prejudices and how I will detail the personality traits. 2. Introduction. This section is a description of the process of my personal and professional experiences that led me to discover the colonized personality. 3. Chapter One. This first chapter describes the colonized personality disorder. 4. Chapter Two. In this chapter there is a description of how the colonized personality has defined the social organization of the Puerto Rican population. 5. Chapter Three. This chapter presents and details the evaluation scale for defining the colonized personality. 6. Chapter Four. This chapter is a description of the differences between a colonized personality and a non-colonized personality. 7. Predictions. In this last section I formulate hypotheses of Puerto Ricans’ future behavior regarding the political status based on the colonized personality.