The Internet and online platforms have become a useful instrument for modern terrorists’ recruitment. Numerous studies explored the online recruitment of Jihadi groups and especially of the Islamic State (ISIS) that managed to recruit over 40,000 fighters from as many as 90 countries. Yet, these studies, focusing mainly on the online platforms and the appeals used, lacked a theoretical framework that can serve the search for the factors explaining process and its success. In this chapter we suggest that the notion of motivational imbalance as a key persuasive appeal in terrorist online recruitment can provide the needed psychological theoretical concept to explain their recruitment strategy. To do so, we examine terrorist online recruitment and its features (stages, type of messages, content of the messages, characteristics of the targets) and relate it to the notion of motivational imbalance. Then we explore the trend of ‘narrowcasting’ (focusing persuasive communication on selected target audiences) and how well it combines with motivational imbalance in the process of recruitment by terrorist groups. Finally, we demonstrate how motivational imbalance has been used in recent Jihadi recruitment campaigns. The evidence presented comes from the contents of recruitment campaigns as well as from the testimonies of recruits.