"The Handbook of Solitude (Coplan & Bowker, 2014) was the first academic volume to specifically explore the many different faces of solitude. Since that time, there has been considerable advancement in the psychological study of solitude, with novel and exciting research focusing on previously unconsidered aspects of being alone. In this edition of the Handbook of Solitude, we are absolutely thrilled to present a blend of new and updated chapters that approach the study of solitude from a myriad of theoretical perspectives and methodological approaches, and with critically important applications for practice and policy. In this introductory chapter, we revisit some of the key historical themes in the study of solitude, consider some of the novel issues that have emerged in recent years, and describe a broad theoretical model of the causes and consequences of solitude. We finish the chapter with an overview of the novel and updated contents of this new volume"-- Provided by publisher.