THE LA ST HA LF-CEN TU RY has seen an explosion of knowledge about the genetic basis of disease: over 10,000 genes have been isolated (OMIM, 1999), and hundreds of genetic tests are clinically available. It was more than a 100 ago that Gregor Mendel described the essential attributes of inherited characteristics of plants, which he called “particulate factors.” However, it was not until the turn of the 20th century that the word “gene” was coined (by the Danish biologist Wilhelm Johannsen, in 1909) to describe the inherited elements. The inheritance patterns of traits Mendel observed were, in the 1940s, attributed to DNA (by Avery, McLeod, and McCarty), and, in 1953, Watson and Crick elucidated the structure of the DNA molecule. Continuing to build on genetic discoveries, scientists have made great strides in sequencing the human genome and understanding the basic molecular processes of all living things. Despite the promises of the Human Genome Project and others to improve health presumably through gene therapy (Verma, 1997; Anderson, 1998), the most widespread application of human genetic discoveries is the developm ent and use of genetic tests to diagnose or predict illness. Genetic information gleaned from tests provides not only risk factors for disease onset, but may also provide inform ation about immutable health characteristics. Genetic information only tells part of an individual’ s health risk profile. Genetic tests deal with probabilities and percentages, generally not certainties. For example, even if a person tests positive for a particular mutation, they may never develop the disease associated with that mutation, even though their risk of doing so is increased. Genetic tests cannot predict the severity of disease. Down’s Syndrome, for example, is easily discovered by chromosomal analysis, yet there is no way to predict the degree of mental or physical disability of the child. And no test can predict the onset age of Huntington’s disease (an adult-onset degenerative nerve disease). New genes are discovered almost every week, and each holds the possibility of prediction. Tests are available for diseases ranging from heritable breast cancer (associated with mutations in BRCA1 and BRCA2), to Fragile X Syndrom e (among the most common inherited forms of mental retardation in males; Warren and Nelson, 1994). One does not choose to be 30% more likely to get cancer, but one has to live with the probabilitie s, possibilitie s, and predictions of genetic testing. It is powerful inform ation, and potentially useful to powerful institutions : military, law enforcemen t, employers, insurers, biotechnolo gy and pharmaceu tical companies, researchers , educational institutions , courts, the governmen t, and others. Although attempts have been made to regulate use of genetic inform ation in all these areas, the longest-run ning policy focus has been insurer use of genetic informatio n. This study examines the impact of legislation on insurer use of genetic informatio n, as seen through the eyes of the insurance commissioner.