The value of comparative genome analysis is becoming increasingly apparent in the derivation of gene structure and regulation data for use in developing treatments for human diseases—both inherited and acquired—and for understanding phylogeny and the mechanisms of evolution. Whole genome sequencing with multiple genome coverage is expensive, and the decision to sequence a specific organism involves questions of quantity versus quality of genome sequencing in the first world and questions of cost in the developing world. In the September 26 Science, Ewen Kirkness and colleagues at the Institute for Genomic Research assess the data obtained from sample sequencing of the dog genome that may provide answers to encourage inhabitants of both worlds (Science, 301:1898-1903, September 26, 2003).