Why do small caps achieve higher risk-adjusted yields than large caps? Why do stock prices increase or decrease upon an index entry respectively deletion? Why does January records higher yields than the remaining months of the year? These as well as other observed capital market anomalies or phenomena could be insufficiently explained by the classical capital market theory, which proceeds on the assumptions that all correspondent information are reflected in the stock prices, all negative effects are directly balanced on the market level and that efficiency of arbitrage principle exists as well as that all market participants act rationally (i.e. optimizing their benefits in the sense of the homo economicus). This motivated some economists and psychologists to include behavioural scientific findings in their research of the influences on the formation of prices on the capital market. In the 1980s the theory of Behavioural Finance was developed, which challenges the homo economicus. Researchers came to the conclusion that humans are not only acting rational, but that they are also influenced by emotions, knowledge and experiences. This new scientific behavioural oriented theory, which is today a separate branch of research, contradicts the classical capital market theory and supplies explanations for the observed phenomena on the capital market. The aim of this book is to demonstrate how human behaviour influences the development on the capital market and how Behavioural Finance serves as an explanation for the empirically observed capital market anomalies. This book begins with the introduction of the theoretical basis of Behavioural Finance and its emergence; tasks as well as aims will be explained in detail. Subsequently, human’s heuristics as well as anomalies and irrationalities in their decision making process will be demonstrated. In the third chapter, the capital market anomalies or phenomena as well as the irrational and behavioural reasons for their existence will be described. The fourth chapter covers empirical evidence for their existence as well as for the insufficient explanatory power of the classical capital market theory. Concluding a critical acclaim, target achievements and perspectives concerning Behavioural Finance will be given.