Â© 2014 Springer International Publishing Switzerland. All rights are reserved. Research into transfer of learning was originally focused on outcomes' evaluation in terms of reaction, learning, behavior, and results. Outcomes' evaluation, widely accepted by practitioners, is criticized by researchers seeking a more systemic approach for assessing the effectiveness of training interventions. As a result, the field of transfer research developed approaches more cognizant of context with a muted emphasis on outcomes. In turn, these approaches were criticized for their lack of tangible evidence of transfer of training. This chapter describes the development of evaluation from its early days up until its current evolution. The original outcomes' model, the Four-Level Model by Donald Kirkpatrick, is described and its contributions and criticisms are discussed. Phillips' return on investment approach (ROI) is also described. An account of how to measure the transfer of training using ROI is discussed. Finally, the implications of using ROI as a measure of transfer are considered.