It is unknown whether or why genetic test reporting confers benefits in the understanding and management of cancer risk beyond what patients learn from counseling based on family history. A prospective nonexperimental control group study compared participants from melanoma-prone families who underwent CDKN2A/p16 (p16) genetic testing (27 carriers, 38 noncarriers) to participants from equivalently melanoma-prone families known not to carry a deleterious p16 mutation (31 no-test controls). All participants received equivalent counseling concerning elevated lifetime melanoma risk and corresponding recommendations for prevention and screening. Both immediately and 1 month after counseling, participants receiving a genetic test result reported greater understanding of their risk, decreased derogation of the risk information, and greater personal applicability of prevention recommendations than no-test controls. Decreased derogation of risk information after test reporting predicted further increases in understanding of melanoma risk and applicability of prevention recommendations 1 month later. Results suggest unique benefits of genetic test reporting in promoting understanding and acceptance of information about hereditary cancer risk and its management.