Scientists and communication scholars should ideally have similar views on public engagement in order for theory to inform practice. This study compares these two groups and investigates the differences in what they believe about public engagement of science. The online survey was administered to one group made up of communication scholars who had recently published in leading science communication journals (N = 362) and another group of natural and physical scientists from three prominent professional science societies (N = 307, 373, 372). Similarities between scientists’ performance, factors that influence engagement activities, and communication objectives were all observed in the results. However, important differences in beliefs about engagement norms as well as engagement efficacy were also found between the two groups. The group of physical and natural scientists rate themselves more positively in their thoughts on engagement norms and their efficacy towards public engagement. The group of communication scholars have higher expectations about the amount of online engagement scientists should be doing. The findings presented in this study offer an interesting look at how perceptions and expectations differ between these two groups that are central to the public engagement of science. Suggested areas of future communication training efforts and future research are explored to address these gaps.