It is common to evaluate scheduling policies based on their mean response times. Another important, but sometimes opposing, performance metric is a scheduling policy’s fairness. For example, a policy that biases towards small job sizes so as to minimize mean response time may end up being unfair to large job sizes. In this paper we define three types of unfairness and demonstrate large classes of scheduling policies that fall into each type. We end with a discussion on which jobs are the ones being treated unfairly. Categories and Subject Descriptors F.2.2 [Nonnumerical Algorithms and Problems]: Sequencing and Scheduling; G.3 [Probability and Statistics]: Queueing Theory; C.4 [Performance of Systems]: Performance Attributes—Unfairness General Terms Performance, Algorithms Keywords Scheduling; unfairness; M/G/1; FB; LAS; SET; feedback; least attained service; shortest elapsed time; PS; processor sharing; SRPT; shortest remaining processing time; slowdown