Does the socially responsible behaviour of corporations affect their profitability? How can corporate socially responsible (CSR) behaviour be measured so as to meaningfully compare firms' CSR performance across industries, e.g. manufacturing and banking sector? Why do "responsible investments" appear to generate excess return? These are just some of the questions that this book attempts to answer by relying on sound analysis and state-of-the-art econometric techniques. The results reveal that CSR activities do not generally have a negative effect on profitability, but that in the few cases when they have a positive effect, this effect is rather small. Interestingly, what appears to greatly matter for the sign and size of this CSR impact is how the individual CSR measures are aggregated. Finally, the study finds that financial markets react strongly and negatively to bad news about companies' CSR efforts, while positive news trigger no reaction. This research has been partly financed by MISTRA, the Swedish Foundation for Strategic Environmental Research. Parts of this work were published in well-established academic journals such as Applied Economics and Sustainable Development.