This paper deals with the third and most disputed principle of John Rawls’s theory of justice: the so-called difference principle. My reasoning has three parts. I first present and examine the principle. My investigation is driven by three questions: what considerations lead Rawls to the acceptance of the principle; what the principle’s relation to effectiveness is; and what and how much the principle demands. A proper understanding of the principle permits me to spend the second half of the paper with (...) exploring the difficulties the principle encounters. I first discuss four well-known objections and argue that all of them, partly or entirely, hold against the principle. I then discuss the applicability of the principle with special attention to the relations among the three Rawlsian principles and the notion of the social minimum. Investigation of the first issue shows that the two other principles leave enough room for the difference principle, whereas in the second case I conclude that parties to the Rawlsian original position would prefer a social minimum principle to the difference principle. Finally, at the end of the paper, I briefly summarize my reasoning repeating its most important findings. (shrink)