The problem of communicating (unordered) sets, rather than (ordered) sequences is formulated. Elementary results in all major branches of source coding theory, including lossless coding, high-rate and low-rate quantization, and rate distortion theory are presented. In certain scenarios, rate savings of log n! bits for sets of size n are obtained. Asymptotically in the set size, the entropy rate is zero and for sources with an ordered parent alphabet, the (0, 0) point is the rate distortion function.