This paper reports on a series of signaling game experiments in which an informed sender can send a costly message in order to persuade an uninformed responder. We compare t he behavior of two subjects pools: 143 undergraduate students and 30 public affairs official s that are professionally familiar with strategic information transmission. The experiments comprised two parameter treatments: one with low costs for sending messages, and one with high costs. Our main conclusion is that there are neither significant nor systematic differences in the behavior of the two subject-pools.