CEOs are investing more than ever in their sales forces, but results aren’t improving. To understand this disconnect, we observed 1800 sales professionals in live sales meetings. We discovered eight sales types. The bad news is that only three of them—accounting for a mere 37% of salespeople—were consistently effective. What’s more, some of the behaviors of the remaining 63% actually drove down performance. But there’s good news, too: The eight types represent behavioral tendencies, not set-in-stone personalities. Managers can effect changes in their current sales people and recruit better team members in the future if they understand the eight types.