Feelings of loneliness are central to the human experience. Therefore, because loneliness is an inherent human condition, operating on a cognitive and affective level, most individuals experience loneliness at some time across the life-span. Loneliness is a unique and multidimensional phenomenon that represents the extent to which an individual’s perceived social network is either smaller or less satisfying than they desire. This book presents current research in the study of loneliness including such topics as loneliness in childhood and consequences for psychosocial adjustment and academic performance; the elderly and loneliness; loneliness in sexual offenders; the influence of age and gender on the experience of loneliness; the loneliness of undergraduate students studying abroad; gay, lesbian and bisexual adolescents and loneliness; and population density and loneliness.