_The Four I’s: Interviewing, Interrogation, Investigating, and Intelligence in Criminal Justice_ is designed to help readers develop the interpersonal communication skills they need to effectively conduct and support criminal investigations. The text provides readers with comprehensive explorations of interviewing, interrogating, investigating, and gathering intelligence. Relying on scientific studies and empirical evidence from the authors’ careers in the field, the book posits that individuals with a proper understanding of these essential elements perform better in their jobs, have higher rates of effectiveness, and achieve better results. The book identifies the similarities and differences between interviewing, interrogating, investigating, and gathering intelligence, providing readers with a process overview, consideration of environmental factors, and recommended approaches for each skillset. Readers learn how to prepare for different types of interviews, how to evaluate non-verbal behavior, how to corroborate evidence and identify false confessions, how to properly approach investigations for property crimes versus personal crimes, the steps for efficient, effective intelligence planning, and more. Written to help readers foster interpersonal communication skills that are critical within the discipline, _The Four I’s_ is an exceptional resource for courses and programs in criminal justice.