The authors have developed a text that reflects the directions Genetics is taking as it heads into the 21st century. This perspective embraces five major themes: 1. the central importance of the genome,as opposed to the action of individual genes; 2. the application of genetics to the improvement of human health; 3. the growing appreciation for the relationships among organisms arising from genetic research; 4. the impact of biotechnology on the accelerating growth of genetic knowledge; and 5. the importance of emerging social and ethical issues related to our use of biotechnology.