This article reports article reports on a mapping study to investigate the C-ROADS Day 1 C-ITS application Green Light Optimal Speed Advisory (GLOSA). In the study, 64 publications between 2006 and 2019 where reviewed and classified according to a schema developed using thematic analysis of the selected publications. Among the findings were that the typical publication evaluates through simulation benefits for the equipped vehicle, leaving considerable gaps in investigations of societal effects. Additionally, there is a lack of investigation on driver behaviour, both for the equipped vehicle and for fellow road users—the ability to accurately model such behaviour is necessary for reliable simulation results.