This research had the purpose to study the effect of call to action use on text ad effectiveness within search engine advertising. The aim was to get an insight in the effect of an advertisement containing a call to action on the ad’s CTR and conversion rate. Therefore, the following research question has been formulated; “What is the effect of call to actions on text advertisement effectiveness within SEA?”.A brief review of existing literature learns what Search Engine Advertising is and that it’s mechanism works on two main subjects. The submitted maximum price per click and the submitted keywords by the advertiser. Together these determine if the ads are displayed whena user conducts a search query. Furthermore the literature explains what the purpose of advertising is based on the AIDA model. With regard to this model call to actions are explained as imperative statements within text advertising which have the purpose to draw thecustomer into clicking on the displayed ad’s and buy the promoted products. Based upon this one could argue that call to actions have an positive effect on the effectiveness an ad has. In line with the call to action purpose, advertisement effectiveness measure within SEA has been determined by the ad’s click-through-rate (CTR) and conversion rate.Besides, a deeper look into keywords has been given. Based on shopping stages theory the argument is that keywords containing more terms have an positive effect on the ad’s effectiveness and the relationship between call to actions and ad effectiveness. This because users in early shopping stages conduct broad information seeking searches and users in latter shopping stages are seeking more specific products, thus having specific search queries.These assumptions are tested and the results are analyzed. Findings with regard to call to actions seem to point in the direction of the assumptions but unfortunately are not significant enough to support this idea. Assumptions with regard to keyword terms are not supported as well, but provide interesting results since the opposite direction of the relationship is showed in contrast to the assumption. Nonetheless, this result is also not significant enough to supportand further research concerning this subject is recommended.