'Think of training as a product that is being sold within the organisation.' That's the message that this paper gives to those who need to raise a budget for online learning. Many believe that e-learning is now the most effective way of getting knowledge into the heads of those who need it. However, if you wish to make a strong case for e-learning within your organisation, you will need evidence. Return On Investment (ROI) compares the investment in a training deliverable with the eventual cost benefits over a specified period of time. This paper describes the traditional Kirkpatrick model of training evaluation and gives you a five-step tool for calculating ROI on your own e-learning initiatives.