Although the great majority of research studies on cyberbullying have been carried out in western countries (Zych, Ortega, & del Rey, 2015), the issue is recognised to be an international one. There has been a tradition of research in the Asian Pacific Rim countries (Smith, Kwak, & Toda, 2016), and growing research in other areas such as South-East Asia (Sittichai & Smith, 2015). These studies raise important methodological issues. How similar, or different, is the phenomenon of cyberbullying in different countries? What are the challenges in making comparisons and comparing rates in different countries? Finally, how can such differences be explained? This chapter will examine societal and cross-national variations in bully and victim rates, and characteristics (such as age and gender differences, types of cyberbullying), across a wide range of countries. Explanations of cross-national differences will be discussed in terms of the five factors in the EU Kids Online model: Cultural values (e.g., Hofstede), Education system (schools, colleges), Technological infrastructure (penetration of mobile phones, smart phones and internet), Regulatory framework (policies, legal aspects), and Socio-economic stratification (GDP, socioeconomic inequality).