Previous research with adolescents has shown associations of body weight and perceptions of body size with suicide ideation and suicide attempts, but it is unclear whether these associations are direct or whether a mediating effect exists. Abstract: To determine if body mass index and perceived weight are associated significantly with suicide ideation and suicide attempts, controlling for weight control practices, and if perceived weight mediates the associations of body mass index with suicide ideation and suicide attempts. Design, Setting, and Participants: Data were analyzed from the 2001 Youth Risk Behavior Survey, a school-based survey administered to a nationally representative sample of students in grades 9 through 12 (N=13 601). Main Outcome Measure: Self-reported past-year suicide ideation and suicide attempts, compared by perceived weight and body mass index category, calculated from self-reported height and weight. Results: Body mass index category was associated significantly with suicide ideation (among all students) and suicide attempts (among white and Hispanic students) without perceived weight in the model but not with perceived weight added to the model. In contrast with those who perceive themselves as about the right weight, students who perceived themselves as very underweight (odds ratio [OR], 2.29 [95% confidence interval (CI), 1.46- 3.59]), slightly underweight (OR, 1.36 [95% CI, 1.03- 1.79]), slightly overweight (OR, 1.33 [95% CI, 1.12- 1.58]), and very overweight (OR, 2.50 [95% CI, 1.73- 3.60]) had greater adjusted odds of suicide ideation. Among white students, perceiving oneself as very underweight (OR, 3.04 [95% CI, 1.40- 6.58]) or very overweight (OR, 2.74 [95% CI, 1.21- 6.23]) was associated with greater odds of suicide attempts. Perceiving oneself as very underweight was associated with greater odds for suicide attempts among black (OR, 2.86 [95% CI, 1.10- 7.45]) and Hispanic (OR, 3.40 [95% CI, 1.54- 7.51]) students. Conclusions: How adolescents perceive their body weight may be more important than their actual weight in terms of increased likelihood of suicidal behavior. Regardless of body mass index, extreme perceptions of weight appear to be significant risk factors for suicidal behavior; important racial/ethnic differences exist. Previous research with adolescents has shown associations of body weight and perceptions of body size with suicide ideation and suicide attempts, but it is unclear whether these associations are direct or whether a mediating effect exists. Abstract: To determine if body mass index and perceived weight are associated significantly with suicide ideation and suicide attempts, controlling for weight control practices, and if perceived weight mediates the associations of body mass index with suicide ideation and suicide attempts. Design, Setting, and Participants: Data were analyzed from the 2001 Youth Risk Behavior Survey , a school-based survey administered to a nationally representative sample of students in grades 9 through 12 (N = 13601). Main Outcome Measure: Self-reported past-year suicide ideation and suicide attempts, compared by perceived weight and body mass index category, calculated from self-reported height and weight. Results: Body mass index category was associated significant ly with suicide ideation (among all students) and suicide attempts (among white and Hispanic students) without perceived weight in the model but not with perceived weight added to the model. In contrast with those who perceived themselves as about the right weight, students who perceived themselves as very underweight (odds ratio [OR], 2.29 [95% confidence interval (CI), 1.46-3.59]), slightly underweight (OR, 1.36 [95% CI, 1.03-1.79] 1.33 [95% CI, 1.12-1.58]), and very overweight (OR, 2.50 [95% CI, 1.73-3.60]) had greater adjusted odds of suicide ideation. Among white students, perceiving oneself as very underweight (OR, 3.04 [95% CI, 1.40-6.58]) or very overweight (OR, 2.74 [95% CI, 1.21-6.23]) was associated with greater odds of suicide attempts. Perceiving oneself as very underweight was associated with greater odds for suicide attempts among black (OR, 2.86 [95% CI, 1.10- 7.45]) and Hispanic (OR, 3.40 [95% CI, 1.54-7.51]) students. Conclusions: HowRegardless of body mass index, extreme perceptions of weight appear to be significant risk factors for suicidal behavior; important racial / ethnic differences exist.