Mobile advertising is one of the most popular applications of mobile commerce, particularly in the form of SMS advertising. However, little is known regarding the effectiveness of such campaigns and the factors contributing to their success. In this paper we aim at identifying factors that influence the effectiveness of a mobile messaging advertising campaign. We draw on established knowledge from traditional advertising, which is adjusted to the principles of the mobile medium and combined with a number of mobile channel-specific attributes. A survey amongst advertising experts (N=90) is then used to investigate the significance of each variable. Through exploratory factor analysis, we postulate four categories of mobile messaging advertising effectiveness factors (Campaign Strategy, Source, Targeting, and Creative Development). Each factor consists of a number of variables, which are collectively hypothesized to impact the effectiveness of a mobile messaging advertising campaign.