The People Code: It's All About Your Innate Motive
By Dr. Taylor Hartman, Ph.D.
I'm not gonna lie to you, friends: I was pretty skeptical of this system when I first heard about it at work. One of my business school professors engrained a deep distrust of "personality types" in general by pointing out that almost all of them except The Big Five lack any rigorous empirical testing. That being said, as I read this book, time and again I saw descriptions that rang extremely true for either myself or my loved ones. It's probably easy to take this too far and use it as some kind of universal theory, but it makes an awfully useful heuristic for understanding why you act the way you do, and more importantly, why other people act in such seemingly incomprehensible ways.
Buy it here.