Although terrorism is a significant social and political phenomenon, research on terrorism lacks methodological and empirical sophistication. Challenges in the availability of data and collection issues result in information gaps on terrorism related topics. This study focuses on two ideologically distinct terrorist organizations active in Turkey, the religiously motivated Turkish Hezbollah and left wing DHKP/C, and investigates why and how individuals come to decisions to join these terrorist groups. In order to explicate these issues, this research examines terrorist group members' individual attributes and background characteristics, factors that help them learn about terrorist groups, and motivational factors that influence them to participate in terrorist organizations. This research also seeks to reveal similarities and differences between the members of two ideologically different terrorist organizations.

This study relies on both quantitative and qualitative content analyses methods, and analyzes 302 documents seized by Turkish Security forces from Turkish Hezbollah (186) and DHKP/C (116) terrorist organizations' cells. Quantitative analyses revealed statistically significant differences between DHKP/C and Turkish Hezbollah terrorist organizations' participants in terms of background characteristics, learning related factors, and motivational factors, and confirm the importance of approaching different types of terrorist organizations as distinct entities in terms of the development of policies and strategies to prevent participation. Qualitative analysis focused on motivational factors and revealed insights into the various, and sometimes multiple, overlapping factors, that promoted the involvement of sample members in their respective organizations.

This study makes an important contribution to the understanding of terrorist actors and organizational activities, and presents numerous implications for security organizations, policy makers, and scholars. It also identifies several of the major gaps in terrorism studies and provides practical and theoretical insight for future research on similar and related topics in terrorism studies.