The purpose of the book is to deliver a critical review of the literature and author's research data relevant for understanding the phenomena of curiosity, information seeking behavior, and novelty seeking. The book is designed to be a comprehensive and systematic lecture of areas related to the main subject in a way that will enable the reader to grasp the notion of development in terms of the evolutionary time scale and ontogenesis. Each of the subjects is explained on the basis of three perspectives: ultimate factors, integrative levels, and aroximate mechanisms. This work is intended to integrate approaches adopted within psychology, ethology, and behavioral neuroscience.