This dissertation explores associations between body mass index (BMI) and self-perceived weight during adolescence and two health outcomes during young adulthood: 1) testing positive for one or more of three sexually transmitted diseases (STD) (Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis) and 2) reporting intimate partner violence (IPV) victimization. Both papers use National Longitudinal Study of Adolescent Health (Add Health) data from Waves 1, 2, and 3. In the first paper, logistic regression models examined associations between overweight BMI, self-perceived overweight, correct overweight perceptions, and misperceived overweight during adolescence and testing positive for one or more STDs (Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis) during young adulthood as determined by urine testing. In unadjusted and adjusted models, adolescent overweight BMI and self-perceived overweight were not associated with young adult STD status among either gender. Adolescent correctly perceived overweight was associated with young adult STD status among males when pooled by race, and among non-Hispanic Black males in unadjusted models. Associations were no longer statistically significant when sociodemographic variables were included in models. Correctly perceived overweight and misperceived overweight were not significantly associated with STD status among females. Future research should explore the associations of interest in this paper with different adolescent body image measures and a wider variety of STD outcomes to determine if associations exist. In the second paper, logistic regression models examined the effects of adolescent overweight BMI and self-perceived overweight on the odds of experiencing IPV victimization during young adulthood. Overweight BMI and self-perceived overweight during adolescence were not significantly associated with IPV victimization during young adulthood among males. Among females, when pooled by adolescent BMI and race, adolescent overweight BMI was associated with increased odds of IPV victimization in the fully adjusted model. When analyses were stratified by race and adolescent BMI, neither adolescent weight concept was significantly associated with IPV victimization among females. Consistent with previous research, longer relationship duration, cohabitation, non-Hispanic Black race, and child abuse were risk factors for young adulthood IPV victimization. Overall, this dissertation contributes to the literature by exploring the effects of adolescent BMI and body image on understudied outcomes.