Today's world is being shaped by migration and globalization at ever increasing rates. As these forces spread, more and more people with different cultural backgrounds and different personalities come into contact and interact with each other. Not only does this phenomenon pertain to how we work and do business together, but it also applies to the people we spend our leisure time with and trust with our private thoughts and feelings: our friends. Insights from cultural and personality psychology into friendship processes are therefore key to understanding and facilitating friendship processes in these current times of diversified multiculturality and accentuated individuality. The present book presents a selection of current international theoretical perspectives and new empirical insights from scholars in cultural and personality psychology on friendship. Apart from chapters that are primarily from cultural psychology or primarily from personality psychology, there are chapters that apply both perspectives simultaneously as well as two explicitly integrative chapters that integrate the book's chapters into an overarching theoretical framework. The forty authors of the twenty-four chapters in this book come from twenty-nine locations in fifteen countries from around the world. The present book is therefore a paragon of internationality and diversity in and of itself and may be a stepping stone to future integrative research projects on the phenomenon that we refer to as "friendship" so collectively but that we experience so differently.