AbstractIrritable Bowel Syndrome (IBS) affects 10%-20% of adults living in the U.S. and accounts for approximately 25% of all visits to a gastroenterologist. Despite the high prevalence and the significant physical, psychological and financial impact of IBS, the etiology of this disorder is still largely unknown. Previous research supports an influence of genetics, family environment and physical, sexual and emotional abuse on gastrointestinal symptoms and indicates the presence of relationships among abuse, IBS and response to stressors. The purpose of this dissertation is to evaluate gastrointestinal symptoms and stress response to a transient naturalistic stressor in individuals with both non-specific and specific risk factors for IBS. This study evaluated perceived stress levels, gastrointestinal symptoms and non-gastrointestinal somatic symptoms in 78 undergraduate students with and without a family history of childhood trauma and/or a family history of IBS before and after an examination stressor. Assessments were completed using both paper-and-pencil and Internet surveys. In contrast to expectations, the study results did not support the hypothesis that a history of childhood trauma moderates gastrointestinal symptoms or perceived stress response to a transient stressor. Study analyses also did not show that a family history of IBS moderates gastrointestinal or perceived stress response to a transient stressor. The results of this study indicate that severity of emotional abuse is positively correlated with total gastrointestinal symptoms and gastrointestinal symptom frequency. This study further demonstrated that symptoms of IBS aggregate in families. This suggests that there is a genetic/environmental component to IBS and that individuals with a family history of IBS might have an increased risk for developing a functional gastrointestinal disorder. Additional research is needed to more thoroughly explore the relationships among genetics, family environment and development of gastrointestinal symptoms. A more comprehensive understanding of these associations will strengthen our efforts to effectively prevent and treat functional gastrointestinal disorders.