Interfaces that let people use natural language — from chatbots based on typing and reading to voice interfaces based on speaking and listening — are wildly popular but wildly immature: They're still far from truly conversational. Companies need guidance from CX pros so that their efforts at creating conversational interfaces help customers rather than driving them away. This short report defines what they are, explains why the bar is high, and lays out the basic — but challenging — principles for making these interfaces human-like instead of robot-like.