This is a white paper I wrote a couple of years ago on the knotty subject of segmentation. I\'ve found that 90% or more of segmentation projects do not meet the original objectives. It amazes me that most of the planet persists in making the same mistakes on segmentation again and again. Many segmentation frameworks last about as long as the tenure of the CMO. Then the CMO is replaced and a new one is launched! I\'ve tried to outline the main pitfalls and how you avoid them. Comments welcome.