A cost-benefit analysis (CBA) is a systematic summary of all the effects and costs of an investment (or similar measure). An analysis such as this is performed in an attempt to ascertain whether an investment is "worth what it costs": in other words, whether the financial values it creates for society are greater than the financial costs it incurs. This study analyses the benefits and costs to society of the two largest components of the Stockholm Trial: the congestion-charging system and the expansion of bus services.