This paper, on the returns on investment (ROI) in training, introduces some practical examples for enterprises or organizations wanting to find out whether the money they have spent or intend to spend on training is necessary. It provides strategies for researchers who would like to undertake research in this area. The paper begins by examining what is meant by ROI and then focuses on what is meant by ROI in training. It borrows from the work of specific researchers and human resource consultants who have come up with systematic models for undertaking this type of evaluation and presents these models in a simple and easy to understand format. Some models for analyzing ROI and ROI in training have been around for a long time, but the principles they demonstrate are still very relevant today. Some step-by-step methods for calculating costs and benefits and simple explanations of the various concepts that underpin calculations of a figure for ROI in training are described. An annotated bibliography contains 29 abstracts of books and journals or magazine articles that deal with ROI in training. (YLB)