Although prior studies provide some insight into the effects of communication factors such as source credibility and argument strength on public perceptions of CCS, comparisons and integration of insights from these studies is complicated by the multitude of different and interdependent factors that influence communication outcomes. Here we provide an overview of these factors, structured in terms of a communications matrix and drawing on experience with CCS projects and studies to date. Using the matrix we organize empirical findings of the effects of four major communication input factors (source, message, channel, receiver) on communication output factors such as, attention, interest, understanding, and attitudes. The resulting 'map' of opinion shapers may guide development of public communication, engagement, and participation in CCS projects. The key message to communicators is that by knowing how input factors influence output factors, it can be decided which features are useful to achieve an intended communication outcome. Obtaining knowledge of input-output interactions requires early public engagement to explore public needs and concerns. Critical to the communication outcome is the extent to which CCS communication is an informed, open and objective public discussion process in which different views on the technology are acknowledged.