Belonging is fundamental to being human. It has deep, deep roots in human history and prehistory. It makes the difference between a life fulfilled and a life of misery. And psychologists are now trying to understand it at the level of their discipline. Within the limits of psychology, Kelly-Anne Allen does a good job of giving an overview of belonging, from the viewpoints of theoretical and experimental psychology and their applications for psychological treatment. The book’s main limitation, outside its brevity, is the rather desperate efforts made by the author to make it seem that the shift onto social media and the concomitatn decline in real-world interactions has not been absolutely terrible for personal relationships and a major driver for the steep rise in loneliness in the 21st century.