Much has changed in the world since the completion of the previous edition of BIOLOGY. In the realm of the biological sciences, the sequencing of the genomes of many more species has had Jeep ramifications in diverso arcas of rescarch, providing new insights, for example, finto the evolutionary histories of numerous species. There has been an explosion of discovery about small RNA molecules and their roles in gene regulation and, at the other end of the size spectrum, our knowledge of Earth?s biodiversity has expanded to encompass hundreds of new species, including parrots, monkeys, and orchids. And during the lame period, biology has become more prominent than ever in our daily lives. The news is filled with stories about the promise of personalized medicine, novel cancer treatments, the possibility of producing biofuels with the help of genetic engineering, and the use of genetic profiling in solving crimes. Other news stories report clirnate change and ecological disasters, new drug-resistant strains of the pathogens that cause tuberculosis and parasitic infections, and famine?crises in the world around us that are posing new challenges for biologists and their allies in the other sciences. On a personal level, many colleagues and I have missed our inspiring friend, the late Neil Campbell, even as our commitment to leadership in biological education has grown. Our changing world needs biologists and a scientifically literate citizenry as never before, and we are committed to working toward that goal.