This week we differentiate between systematic and unsystematic risk and explain how the expected returns that are reflected in the prices of assets should be linked to only one type of risk. We illustrate how the Capital Asset Pricing Model might be used to link systematic risk with expected return and then discuss the empirical shortcomings of the model. This leads to a description of more advanced models and we conclude with a review of survey evidence that considers the approach taken by finance mangers of large listed firms in practice.