The scientific field which focuses on the study of mental behaviour and processes of non-human animals is referred to as comparative psychology. It explores the behavior of various species ranging from insects to primates. The important topics of study in comparative psychology include individual behaviour, reproductive behaviour and social behaviour such as locomotion, tonic immobility, developmental psychology and behavior genetics. Comparative psychology is also concerned with the study of the behavioral similarities and differences among all living beings. It plays an important role in various other fields such as medicine, animal cognition and behavioral ecology. This book traces the progress of this field and highlights some of its key concepts and applications. It presents researches and studies performed by experts across the globe. Through this book, we attempt to further enlighten the readers about the new concepts in comparative psychology.