||This paper summarizes published research studies, technical reports and codes and standards related to the visibility (i.e., conspicuity and legibility) of signage. In the summary that follows, publications are grouped and discussed according to several different topics. First, the typographic and symbolic characteristics of signs and the information they carry are described (e.g., letter size, font selection, etc.); second, photometric, colorimetric and temporal properties of signs as they affect visibility; finally, environmental considerations (e.g., daytime versus nighttime viewing, whether a sign is located in a rural or urban area, etc.) as they influence sign design are reviewed. Annotated summaries of each publication in the literature review are included at the end of this paper.