Often persuaders have a richer understanding of the world than their audience. This paper models such situations by letting persuader and audience have prior beliefs with different supports. This asymmetry adds unexplored aspects to the persuasion problem: Persuaders can hide their superior knowledge or surprise their audience with unexpected information; After surprises Bayes’ rule cannot describe the audience’s response. The paper examines persuaders’ incentives to hide and surprise and their resulting communication strategies. Moreover, it derives necessary and sufficient conditions for persuaders to surprise their audience as well as to hide some information.