This study proposes to identify factors influencing decision-making regarding genetic testing for Hereditary Nonpolyposis Colorectal Cancer (HNPCC) and the psychological and behavioral outcomes of the testing process. HNPCC is an inherited form of cancer that predisposes persons in such families to multiple kinds of cancer, most notably colon and endometrial cancer. Biological relatives in families with a known HNPCC mutation complete a baseline questionnaire assessing knowledge, expectations, mood, attitudes, perceived cancer risk, cancer worries, family relationships, spirituality, coping and health beliefs. Participants are then provided with an educational/counseling session focused on HNPCC, the availability of genetic testing, its risks, limitations and potential benefits, and cancer screening recommendations for families with HNPCC. Participants are then presented with a choice of whether or not to undergo genetic testing. Those choosing genetic testing undergo a separate informed consent specifically focused on the process of genetic testing and the potential risks, benefits and limitations of genetic testing. Psychological and behavioral outcomes are reassessed through telephone questionnaire at 6 months, 1 and 3 years following risk notification or the decision not to undergo testing. For those receiving genetic test results, notification occurs in person along with discussion of available surveillance options. Follow-up counseling and support are provided for all individuals participating in the study. To date, 388 individuals have completed baseline questionnaires, 346 individuals have completed 6- month follow-up questionnaires, 331 have completed 1 year questionnaires, and 149 have completed 3 year follow-up surveys. Within the last year, we have initiated an addendum to the parent project that aims to characterize the family communication and support system and how the structure of this system is associated with decisions to undertake testing and cancer screening practices. Family system variables are assessed via a brief telephone interview. Additionally, genetically at risk, but non-participating family members and relatives not at risk for inheriting an HNPCC associated gene mutation will be recruited through their participating relatives, to consider completion of a single, brief questionnaire and the family system interview. The non-participant questionnaire assesses demographic information, attitudes/concerns towards genetic testing, percieved risk of cancer, cancer screening behaviors, and characteristics of family communication about HNPCC. To date, 122 individuals have completed the non-participant survey and 246 have completed the family systems interview.