In the latter decades of the 20th Century, education was thought to be the key to unlocking the human potential of developing countries and enabling them to ‘take off’ on a modernising trajectory. In many countries around the globe, significant sums have been devoted to expanding access to education and on improving the quality of inputs. In recent decades, however, this investment in education has increasingly come under scrutiny from economists who question the efficiency and effectiveness of many programmes. Open and distance learning institutions have not escaped this critique and must justify their existence by quantifying their cost-effectiveness relative to conventional education. This unit explores these issues and outlines the calculations that can be made to establish the relative efficiency and effectiveness of ODL.